Macroscopic Editor, Progression, and Principles

Ah okay, makes more sense. I again wonder about how widely applicable and derived this system would be, but having it essentially determine basal statistics is a solid idea that should be implemented regardless. And nonetheless, it is adequate for the prototype.

That is true, but again, the mesoderm is much more than just skeletal muscles and the skeleton itself. Mesodermal tissues work with root endodermal tissues to create advanced organs, like the lungs, stomach, large intestines, etc. Practically, this translates into questions like this one: how would we limit progression through the respiratory and digestive systems so that players aren’t a mixed bag of an advanced respiratory/digestive system with a lack of mesodermal tissue, which is scientifically inaccurate based on life as we know it? It’s a bit more involved than just what is energetically affordable for an organism it seems, so we definitely have to be mindful of germ layers in atleast some capacity.

Ultimately, I guess the question is how to make the unlocking of mesoderm-analogous tissues in the macroscopic stage the significant jump it was on Earth.

You do indeed understand correctly, and it seems the topic of spicules is a heavily researched topic in scientists because of the interesting implications they have on animal development. A skim of the spicule wikipedia page seems to indicate that some scientists consider them to be a simple version of more advanced skeletal structures in the “higher” metazoans (a very primitive form of biomineralization). Sponges are really odd to address because some scientists consider them to not have truly specialized cells (spicules are much less distinct and specialized than bone cells it seems). Our understanding of animal evolution that far back is also murky - there are a lot of ideas of what the transitional diploblast or triploblast looked like for example - so we definitely need more research.

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Good question. Evolving muscles could more or less automatically greatly improve the efficiency of the respiratory and the digestive system, since musculature can greatly improve the rate at which these systems exchange their respective contents. But that‘s probably only part of it.

But yeah, this system needs very long and careful thought since it‘s one of the most pivotal parts of our game.

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After reading through the ideas and thoughts provided by Deus, I have decided to go about designing the macroscopic editor proper, and how the player’s creature can be modeled. I have taken what I have learned from player interaction with our prototypes made by Hhyyrylainen to reimagine the editor as (I hope) a more intuitive form compared to previous iterations.


The macroscopic editor is the apex of creature creation in Thrive. It is at this stage that the player goes on to create a complete being using all that they had learned and created in past stages. Our goal is to make sure that all of the design choices the player has made in previous stages continue to play a part here.

Before I begin, I will go over each editor and how they relate to each other. This is optional reading, and may be skipped over.

Optional Text Dump

Microbe Stage
When the player first reproduces, they are presented with the microbe editor, and a single hex of cytoplasm.
From the very beginning they are assaulted with a large array of options and potential choices that can be quite overwhelming. Luckily, the life of a microbe is not immediately demanding of utmost efficiency and so they are granted some freedom to experiment and learn.

This stage teaches the player how to balance their energy consumption, the foundations of building an efficient cell, and how to occupy a given niche using their parts.

Multicellular Stage
Having successfully built a cell capable of surviving the trials of the primordial soup, the player will now have accessed the multicellular editor.
Suddenly the player is presented with an entirely new layer to the editor! Not only are they able to plan out a body-plan for a creature larger than one cell, but they are also now able to create multiple variations of their original cell.

This opens up a significant level of customization, but also more complexity that they must learn.

This stage teaches the player how to manage different cell and tissue types in one creature, how to coordinate energy balance and metabolism between specialized cells, and how to form a cohesive body plan.

Macroscopic Stage
Having survived to become an increasingly elaborate organism, the player will have now accessed the macroscopic editor, and final stage of customization.
The player is suddenly no longer constrained to a 2D plane, and is now able to form a completely cohesive body structure instead of a loose cluster of specialize cells.

In this final stage, the player will learn how to use their specialized cells to create organ structures throughout the creature, coordinate organs to form organ systems, and form a cohesive creature made of flesh and blood.

As of now, we have a macroscopic editor prototype, that while fun to use, is ultimately a messy and unintuitive affair. The player begins with a nondescript cluster of metaballs loosely resembling their multicellular body plan, upon which more cells can be added to the pile by haphazardly attaching more.

What this editor currently lacks is a form of concrete and cohesive structure that the player can build onto. And so, the following concept aims to rectify this shortcoming.

By introducing hierarchical definition to the metaballs, we can easily grant each part of the player’s organism an identifiable definition and shape. The resulting layout is easy to understand, and easier to modify. This also allows us to better designate parts for mechanical and animation purposes.

Metaballs will be categorized into three separate varieties and levels of hierarchy.

Central metaballs are the backbone of the organism, and form the overall body-shape. Centrals can only be connected to others of the same hierarchy, and at least one must always exist within the creature. New centrals are created by extending from another, creating a “spine”.

Distal metaballs are the accents and details of the organism, and grant the organism detailed shape. Distals must always be connected to a parent central ball either directly or via another distal. These balls act as direct extensions of their parent centrals, moving with their parent’s motions. Copying (Or removing) a central will bring all of the attached distals alongside it, allowing for effective segmentation and expansion.

Limb metaballs are strictly used to define parts of the organism as posable appendages. This allows players (and the game itself) to easily recognize and define specific parts as animated limbs instead of static parts of their torso. Limbs may be placed upon distals or directly upon centrals, while only other limbs can be placed upon themselves.

With this metaball hierarchy in place, the macroscopic editor becomes navigable and comprehensive to both the player and computer.

A question remains however; Where will the player’s specialized cells come into play here? How will they be assigned throughout the organism if not ball by ball? The answer to this is organs!


Each cell created by the player will be assigned either to metaballs (both central and distal) within the organism as specialized organs, or as the dermis that composes their hide. Each metaball can contain several organs at once or none at all, allowing for clever allocation of internal characteristics in the organism.

Organs can take on various forms that define their basal characteristics, which are then further modified by the cells that compose them.

Connective organs such as nerves, muscles, blood or fat. These broadly defined organs span the length of a bodypart, and grant various benefits based largely on the characteristics of the cells themselves. Most notably to bridge between other organs. They are the default organ type that the player’s specialized cells will initially be defined as upon entering the stage.

Cavity organs such as stomachs and bladders. These are used to hold and/or process matter that otherwise wouldn’t be held within the cells themselves.

Orifice organs are gateways between the organism’s internals and the outside world for better and worse. These are used to exchange large amounts of matter with the world at large.

Sensory organs are externally exposed receptors such as eyes, ears, and noses. These are used to analyze the surrounding world, but as such are also quite vulnerable.

Dermal organs are the skin and armor of an organism. The primary dermal cell encompasses the entirety of the organism unless otherwise specified on specific metaballs by creating a dermal organ which overrides it with another cell of choice. This can be used to create armored portions of the body, or perhaps toxic regions.

By default, the first cell in the player’s organism becomes the dermis, while the cells derived from the original become organs held within the initial central metaball. The player can then remove these organs if necessary, or choose to expand them into more specialized and effective roles. Organs are copied or deleted alongside their parent metaball, but can also be copied and deleted between metaballs themselves.

The attachment of organs to the metaballs themselves allows for relatively intuitive customization analogous to the upgrades system for organelles in the cell editor. This grants familiarity and initial understanding for players, while also avoiding the pitfall of having to loosely attach physical organs to a body.


By creating a hierarchical structure for metaballs, the macroscopic editor is more easily understood by player and computer both. The player’s specialized cells from prior stages become the skin and organs of the creature, maintaining continuity and carrying over the player’s past choices. The overall design invokes analogies of concepts already explored by previous editors, allowing a sense of familiarity and understanding.

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Regarding limbs I was thinking that the player would be able to select any connection between two metaballs and designate that as a joint. And also at that point the player could select the muscle type to go there.

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Here is an example of how @Buckly’s method of dealing with organs can look in game.


As Buckly suggests, a player will be able to create a digestive system by adding organs to their creature’s metaballs. The player must first place a gastrointestinal tube on a metaball.

Once this gastrointestinal tube is placed, the player will then be able to place more advanced digestive organs on their gastrointestinal tube, and otherwise modify their tube, to make a more advanced digestive system. More advanced organs require the basal digestive tube to be evolved first.

Incomplete Digestive System

Incomplete digestive systems only have one hole through which food goes through and waste is excreted from. It is referred to as an “incomplete” digestive system because the gastrointestinal tube doesn’t go all the way through the organism into an anal opening.

Incomplete digestive systems are found in most diploblastic organisms, such as jellyfish, and the most simple triploblastic organisms, such as flatworms.


  • Simple. Requires relatively less energy/resources, so is good enough for simple and low-energy lifeforms.
  • Easier to Circulate Resources. Incomplete digestive resources can also serve roles similar to the circulatory system, which makes the secondary system not as necessary. This is also due to the relative simplicity of organisms with incomplete digestive systems, however.


  • Limited Storage Capabilities. Because both food and waste are released through the same hole, organisms can’t really afford to mix the two. This requires a more constant input of food.
  • Weak Waste Management. Organisms with incomplete digestive systems oftentimes need to get rid of undigested food due to a buildup of waste, reducing efficiency of the digestive system as a whole.

Complete Digestive System

Complete digestive systems have both a mouth and an anal opening. The gastrointestinal tube runs completely throughout the entire organism, allowing enhanced compartmentalization and specialization within the digestive system.

Complete digestive systems are found in most triploblastic organisms, such as the arthropods, vertebrates, and molluscs


  • Efficient. Because waste and food are processed well separately in complete digestive systems, more nutrients are absorbed.
  • Allows Greater Specialization. Advanced organs, such as intestines and stomach cavities, now make sense to evolve, as food can now be stored separately from waste. More storage and digestive versatility can be applied to an organism.


  • Less Circulatory Capabilities. Although partially due to the advanced nature of most organisms which have complete digestive systems, complete digestive systems require a more well-developed circulatory system to pick up the slack.
  • More Resource Intensive. With greater specialization comes more tasks to fuel. Complete digestive systems usually need greater amounts of energy to maintain, although they can atleast store food more efficiently for future consumption.

In Thrive

In Thrive, a digestive system is incomplete if a player doesn’t extend their digestive tract completely through the organism. An incomplete system will have somewhat bumped circulation stats, but will have limited digestion stats due to its inefficiency. Players will have to spend the MP needed to get their gastrointestinal tube completely throughout their entire organism to have a complete digestive system.

A complete digestive system can be unlocked in Thrive when a player spends the MP needed to fully extend their gastrointestinal tube throughout the entire organism, resulting in an anal opening. Digestion will be bumped significantly, while circulation will be slightly reduced, incentivizing the development of a circulatory system.

A complete digestive system will also allow the player to develop more advanced digestive organs, opening up more parts that will allow broader diets and greater storage.

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With the plans for the overall body customization planned out, I have decided to approach customization of the dermal covering of the organism. The dermis plays an analogous role to the membrane of a cell, separating the organism’s internal environment from the external environment it inhabits, so it’s a pretty important aspect of evolution.
Keep in mind that this is a this is a rough draft, as there’s much to consider and discuss before we nail down the exact designs and forms of customization.

Integuments Tab

In Thrive, the dermis is not tied to a specific metaball within the creature unlike other organs, and instead is edited through the integuments tab.

The integuments tab presents players with a variety of customization options that can have a big effect on their organism such as dermal thickness, dermal coverings, and the nature of the dermal cells that compose the skin.

The nature of a player’s integumentary system can have a large effect on their osmoregulation, ability to passively absorb nutrients from their environment, ability to respirate through their skin, defensive capabilities, and more.

The integumentary system will play the largest role in a species’ tolerance to new environments, and will likely be the first recipient of adaptation before further specialization due to relatively lower cost and larger impact. It is easier to develop a thicker coat than to generate more body heat after all.

Dermal Cells:

When the player enters the macroscopic stage, the first cell the organism starts with, the stem cell, will become the dermal cell while all other specialized cells become the first organs. Alternatively, the most numerous cell could be chosen to become the dermal cell. Which ever proves to be most effective and possible to implement. The customization of dermal cells could also potentially be entirely avoided for ease of understanding and simplicity.

The dermal cell is what composes the organism’s skin, and benefits from being exposed to the outside environment, while protecting the organism’s more sensitive innards. It’s characteristics can decide what color flesh the organism has, if an organism is toxic on contact, if it’s skin is coated in mucus, or even if it can photosynthesize.

Due to the nature of dermal cells, some of their organelles will have new purpose compared to internal organ cells. The specifics of which are described below;

  • Slime jets; Create a continuous mucus coating like sebum or slime on the organism that can protect from various threats.
  • toxic parts; Depending on upgrades, makes skin poisonous to eat or toxic to touch. cnidocytes create a stinging touch.

Dermal Thickness:

Dermal thickness is simply a measure of how thick the organism’s skin is, and can be edited by a basic slider much like fluidity/rigidity in the microbe stages. Thicker skinned creatures will have more health, resistance to environmental conditions, and lower osmoregulation costs.
Thinner skinned creatures will be able to passively absorb compounds from their surroundings through their skin, respirate through their skin, and regenerate health more quickly.

Increasing thickness effects the following stats;

  • Total health +
  • environmental tolerance range +
  • osmoregulation cost -
  • Regeneration rate -
  • Passive compound absorption -
  • Respiration rate -

Smaller, simpler creatures can easily benefit from thinner skin as they will have little to no need for an advanced respiratory system. Larger creatures will likely need to develop thicker skin as the benefits of thin skin are diminished by increasing respiratory needs and osmoregulation.

Dermal Covering:

Coverings are features that provide an extra layer of defense to an organism, such as fur, scales, osteoderms, feathers, scutes, and bare skin. Their implementation and function is mechanically synonymous with membrane selection on the cellular level, with the player selecting a covering of their choice to be applied over the organism.

Coverings have a significant effect on the environmental tolerance range of an organism, but can also provide additional effects to damage resistance, speed, or even possibly effective mass.
Loose concepts for various coverings and their potential effects are listed below (Note that these ideas may be totally irrelevant until we have a firm understanding of the range of statistics organisms will be subject to);

Bare skin: No special benefits or malises.
Scales: Provide a small layer of physical protection and help dissipate heat, increasing max temperature range at the cost of cold vulnerability. reduce drag.
Scutes: Grants good physical protection, reduces speed due to decreased range of mobility.
Feathers: Help retain heat, reduce drag with little to no malaise.
Osteoderms: Functionally similar to scute stats wise.
Fur: Provides great environmental tolerance against both heat and cold. Increases drag.

In the event that dermal cell customization is present, the types of covering a creature can use may potentially be limited by the membrane type of their dermal cells. Such as chitin organisms using cetae and chitin plating, or cellulose organisms using bark and suberin.

Dermal Features:

Features are an additional and mostly cosmetic layer to covering customization. Features include localized tufts of fur, bundles of scales, etc. Players are able to place these down to create features such as manes, crests, flashy plummage, and more to customize their organism. These features could play a large role in differentiating sex or other alternate forms of a species without drastic changes to morphology.

Final Thoughts

Customization of the outer skin of an organism is an important avenue of differentiation and adaptation for species and player alike, and has a large bearing on environmental adaptation. Therefore it is important to provide such options.

I personally feel that we should forgo specifying a specific cell type for an organism’s dermis as it creates an intensive amount of complexity that we honestly should avoid for what is otherwise an accessory addition to the editor. On Earth, most species feature a complex array of specialized cells and tissues that would lead to a depth of customization equal to the organs, thus effectively doubling editor complexity. It’s also worth mentioning that many dermal features are extracellular, or tied to cell parts like the golgi apparatus which makes design and mechanical differentiation pretty complicated.

Adjusting the dermal thickness is another aspect I have seriously considered, but ultimately feel would be nothing more than a feature that would punish players for not understanding it’s importance more than anything else. Instead, it may be better to include it’s stats as a natural consequence to increased size, rather than a soft requirement.

I personally feel that the best way to handle this customization is to simply present players with a list of unique coverings to throw on their organism, a way to adjust coloration and patterns, and be done so as not to distract from the rest of the editor.

Things to consider:

  • There are many ways to go about dermal customization, creating substantial risk of unneeded depth and complexity that serves more to disorient players, so care needs to be taken to ensure that dermal customization is quick and easy to utilize so as not to distract from other areas of customization.
  • Features such as shells, horns, or spines may need additional thought and consideration.
  • Various covering types are unique to different cell types in reality, thus there may be a need for deciding what type of cell membrane comprises the dermis regardless of whether the microbe editor is used.
  • Incorporating the microbe editor for dermal customization is potentially more complex than necessary
  • Customization of dermal thickness is potentially unnecessary, forcing players to utilize a slider as their species grows in size, and thus creating an extra step to an already complicated process.
  • Placing features may possibly require special handling compared to the placement of body-parts.
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Feathers also covering just part of the body seems like something players would really want for flexibility of creation reasons and this system seems to skip over that, so I can’t say I’m a super big fan of just having an overall skin options.

Ah I had a nagging feeling I was forgetting something!

Having different textures on different parts might be complicated, but I do not know for sure. @Nunz might know if it’s feasible to blend textures (probably not) or if we just overlap different metaballs instead of fusing them.

As for handling placement; We could either allow players to select specific metaballs while in the integuments tab to change their covering, or have the covering as a customizable “organ” in the organs selection box on each metaball.

Blending textures is quite feasible. You would just need points to define where different textures are located and you could use something like metaball math or convolution in the final texture generation to smooth between them. The compound plane already kinda blends textures.

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After some recent brainstorming and discussion; I now believe I’ve nailed down a good and proper design for the macroscopic editor. A design that is far more streamlined and simple to use than the previous iterations at the very least.

I’ll be going over the general mechanics of the editor, and not necessarily deep into the fine details and balancing just yet. This is so that we can have a firm and solid foundation that we can further build upon moving forward.

ᶠᵒʳ ᶦᵐᵐᵉʳˢᶦᵛᵉ ʳᵉᵃᵈᶦⁿᵍ ˡᶦˢᵗᵉⁿ ᵗᵒ ᵗʰᶦˢ ᵗʰᵉᵐᵉ ᵃˢ ʸᵒᵘ ˢᶜʳᵒˡˡ

The Structure Tab

The first tab the player will see when first entering the macroscopic stage; The structure tab allows players to assemble and shape their organism through the use of our favorite spherical objects, the metaballs.

As of my current designs, there are two categories of parts available in this tab; the Body parts, and Feature parts.


The first and most important category of parts is the Body category, which contains parts used for creating the overall body-plan and animation skeleton of the organism. They are undoubtedly the most important, and need to be placed before anything else can be done in the editor. presenting the player with the following parts;

Central Metaball:
These metaballs act as the spine and primary body of the creature, and the platform upon which all other parts are attached. The organism must always have at least one primary metaball. To maintain a cohesive form, they can only be attached to other central balls and copying one will copy all secondary parts directly attached to it. Finally; central balls can only be attached in a direct chain pertaining to your organism’s symmetry (Bilateral would only be a straight chain. Think worm versus starfish). This is to prevent the central “spine” from branching out incohesively and potentially making for difficult procedural animation.

Distal Metaball:
These metaballs are used to form secondary details specific to the central metaball they are attached to, such as horns, branches, ears, or any other passive structure that might protrude from the organism’s body. Distal balls can not only be attached to central balls, but also limb and other distal balls as well. Their primary purpose is to provide additional shape to the organism while maintaining a cohesive form for gameplay purposes.

Limb Metaball:
Instead of providing a static shape like the previous two, the limb ball is used to form animated limbs for use in movement and environmental interaction, A single limb ball can create a stumpy leg, and attaching more can create joints for an increasingly sophisticated limb.

Recess Metaball:
Unlike the previous metaballs, the recess is a “negative” metaball, which means that instead of forming an anchor for the organism’s shape, it creates a pit or divot in the organism’s body. This allows players to create concave or other complex shapes that would otherwise be difficult to form with basic metaballs. Recess balls only effect the balls they are directly attached to (Assuming that’s possible…), allowing for some advanced editing techniques. You cannot attach any additional metaballs to a negative one.

Orifice Metaball:
Another negative metaball, the orifice ball looks identical to the aforementioned recess ball (Except maybe revealing exposed flesh or darkness in the created recess?) but with added mechanical functionality. These balls are used by the player to create functional mouths, nostrils, slime ducts, and more. Players will need to use orifice balls whenever they want to have a method of quickly exchanging resources with their external environment in larger amounts.


Unlike the body category, features encompass a broad assortment of parts that have specific shape or material appearances. These parts are placed directly on the skin of the organism (But will still be connected to a parent metaball corresponding to their placement) and are primarily used for providing cosmetic options for the players. Some parts however, may still provide changes to the organism’s stats.

Some examples of features are included below;

Fur clump:
A cosmetic part that can be used to create manes, crests, tail tufts, and more. The fur clump resembles a raised clump of fur rising from the organism’s body.

Scale Plates:
Thick raised scales that jut from the organism’s body; These plates can be used to provide organisms with a rugged armored look.

Potentially an example of a more functional feature, the shell is a large mineral structure attached to an organism for defense. Soft bodied organisms may even potentially be able to withdraw themselves into their shell, while more solid creatures can only rely on it as a shield.

The exact specifics of features remain unclear for me. It may be better if they are included in the appearance tab instead, or perhaps they should be split into two different categories or even both tabs as well. I will need to discuss this at a later time.

The Rooting Plane:

With the inclusion of sessile life in Thrive, I had to consider how we might differentiate flora from fauna in Thrive. The distinction is not an easy feat, especially considering how truely alien worlds in Thrive may turn out. So for now, my only answer is the inclusion of a rooting plane.

This tool is used by players and AI alike to determine how much of an organism is submerged in the local substrate of it’s environment. Submerged portions of an organism are able to passively absorb nutrients and other materials from the substrate depending on their adaptations, but prevent the organism at large from moving from it’s place. AI would probably only utilize this feature if they have decided to become sessile in behavior, but players can place the rooting plane at any time by clicking the associated button and “placing” the plane at their preferred height.

The rooting plane basically separates the organism into two different environments, with the top half being exposed to atmopsheric elements and wildlife, while the lower half is protected from most threats and is able to tap into geological resources at the cost of limited respiratory efficiency and other resources.

Rooted species cannot move, and could be generated as part of the world’s terrain features and resources instead of active animals, allowing for the generation of what could potentially be described as forests, or at least shrub-lands. To maintain consistency, we could potentially discourage AI from flipping between the two states somehow and avoid walking tree situations between generations.

The Internals Tab

Next up is an equally important tab for the player; centered around organ customization. All of the cells designed by the player find a new home here, where they are used to assign special functions and processes to the metaball they are placed in.

To create an organ, the player must select one of their available tissue types and then left click on a valid metaball to place the organ. Selecting a tissue type will highlight any metaballs that already possess the tissue. Right clicking any metaball opens a context menu displaying all tissue types inside of it, allowing the player to delete or move them.

Each metaball (With the exception of limb, orifice, and recess balls which can contain none) can contain any number of organs. However; each additional organ will decrease the efficiency of all processes (Or perhaps some other form of malaise) tied to that specific metaball, so smart distribution of organs is important. Organ capacity between metaballs could potentially be limited by type, or perhaps size.

Orifice balls cannot directly contain specialized tissue types, and instead expose the tissue types of connected metaballs to the outside environment for better and worse. This allows your organism to eat and digest macroscopic foodstuffs, or to more easily respirate through thicker skin.

When the player first enters the macroscopic stage, all of their specialized cells (or at least the placed ones) will be clustered together inside of a single central metaball, so establishing a hard limit might complicate things, but soft caps might be too punishing as well. Play testing and prototyping might be needed before deciding on a specific course of action.

The Appearance Tab

Much like the membrane tab from the cell editor, the appearance tab is used to customize the outer covering of the organism. Unlike the previous stages however, the player is able to utilize multiple types of coverings as needed.

Integuments are specialized body coverings that shield (or expose) the organism from it’s environment. These will play the biggest role in adapting to new environmental conditions and thus allowing species to occupy a larger range. They can also help a species better survive attacks from predators, or passively absorb nutrients from their surroundings.

By selecting one of the available integuments, the player will then be able to click any metaball to apply their chosen coating to that part of the organism. This can allow players to create armored limbs, or exposed roots for their organism.

Right clicking a metaball while in this tab will select it, displaying it’s current color codes and the name of it’s current integuments. From this context menu, you can copy and paste integument/color options to other metaballs for ease of use.

I hope that these concepts adequately provide a stable and solidified plan for our macroscopic editor going forward, as well as easy to use for players. The macroscopic editor is the final organic editor in the game and possibly where players will be spending most of their time in the creature stages, so we must be very considerate about it’s accessibility and practicality.

I would like confirmation from our programming team about the feasibility of it’s implementation and the work that might be needed to make this concept a reality when possible, and of course I would like to hear everyone’s thoughts on the concept and how agreeable it is.
Should everyone be in favor of this, we can begin filling in the finer details of the editor, and finally move on to the gameplay side of the macroscopic stage.


It’s a general comment, but I’ve always wondered: if we’re aiming for an “Earthlike” progression of life, won’t most of these buttons not get used for most of the game? The last time tetrapods gained a new limb metaball was before we crawled onto land. Most of the evolution we think of in complex animals is really fine-tuning existing structures, not sticking on new parts.

Now if this is just a focus on Macroscopic and we’re trying to focus on the Cambrian explosion where everything is kind of the same jelly critter on the outside but with wildly different arrangements of jelly parts, my argument probably holds a lot less merit.


I think that’s more a question specifically related to progression more so than the underlying mechanics of the macroscopic editor. After trying to make an editor concept while trying to keep progression (specifically, early eumetazoan evolution) in mind, I can say it’s pretty difficult to create a universally applicable editor by limiting focus to a specific era of evolutionary history while trying to extrapolate these findings to other eras of evolutionary history at the same time. Like Buckly has done, I think it’s better if we create general principles and envision general mechanics first, then think of specific case studies and refine the details as we go along, which is something I’ll be focusing on.

Also something of interest: Williston’s Law. A user on the community forums in this thread (Questions about the realistic implementation of repeating parts/segments (and Williston's law) - Multicellular Stage - Thrive Community Forum) put it this way:

“most organisms have ended up with their characteristic arrangement of parts by first evolving many similar parts and then specializing or losing those parts over time.”

Hence, for example, many types of bony fish having more fins than tetrapods have limbs, or the ancestor of arthropods tending to have many more limbs than current arthropods such as was seen in trilobites. Note that Williston’s Law isn’t necessarily canon - currently scientists prefer explanations of variances in evolutionary rates more than general principles of morphological complexity - but it could be a line of thinking which is implemented well in Thrive given the more artificial nature of our evolution. It also reveals that early on in metazoan evolution, experimentation with limbs was rather frequent; it was complexity which transitioned the focus more to tweaking existing structures rather than creating entirely new ones.

I think ultimately that we’d want to have a split between how we treat the creation of limbs (initial investment) and the modification of limbs. We’ll probably want the initial investment to create a limb be more expensive than the modification of limbs in terms of MP. We’ll also probably want to vary the cost of both of these depending on the player’s morphology; so for example, a vertebrate analogue will have to spend a lot more MP than an arthropod analogue to create or modify their limbs. We’ll also probably want to balance/calibrate states related to things such as movement speed or something so that as a player’s limbs get more complex (perhaps in joint count?), they’ll be encouraged to have different limb structures. So for example, vertebrate limbs would be most efficient in terms of speed with either two or four limbs on the ground, with 3 joints in each limb. Arthropod limbs will have slightly more leeway (ants have 6 limbs with 3 joints in each limb, whereas tarantulas can have 7 joints in 8 legs), with more joints and limbs reducing speed but increasing agility for example. These two factors combined should allow us to encourage players to prefer spending MP on the editing of limbs after a while.

But in regards to more specific features that showed up later in evolutionary history, such as the evolution of fur and the such, you have a valid point. We should probably think of a sort of unlocking method in that regard.

PS: I would also like to note that’s vertebrates fundamentally have inherited a development pattern from their ancestors that makes it genetically harder to coordinate the development of additional limbs too. So we do have some grounds of, after a certain point, abstractly bumping the costs of creating limbs for organisms with an endoskeleton.


A bit late to the party, I know, but if it really comes down to it we could potentially end up hiding parts the player cannot utilize in later stages of the… stage.

Obviously we will need a way for the player, and autoevo, to create new limbs at some point, not to mention freebuild which should remain pretty unfettered. So I believe the overall features of the editor are fine, we just need to consider how it changes while the player progresses.

One idea of my own I’ve been toying with, is the idea of committing players to a sort of progression path tied to their choices. These would lock them out of certain parts, but unlock others. The first of which would arise in the transition between microbe and multicellular. Whichever membrane-type their cell possessed would become the defining type. They would no longer be able to alter their membrane type, but may gain access to new associated features. For instance, cellulose organisms would have access to bark and trichome coverings later on, but would not have fur or scales.

The development of advanced bodily support too could be a part of this. endo/exoskeletons would prevent the player from creating brand new limbs, forcing them to creatively alter the limbs they already have. It would basically be the crossroads between …whatever and a proper animal. Not sure what we could give in return though…

I’m sure we can all agree that it would suck if after progressing you just suddenly lose access to parts, it would be pretty jarring. But as organisms become more complex they can no longer throw new limbs and bones on themselves willy nilly, so we would need to make sure the player always has some form of tradeoff in return.

Whatever the case may be, it’s certainly a matter of progression that we need to consider. I think the editor concept I have outlined is fine for a general overview for the future.

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I thought about Bucklys suggested macroscopic editor interface and overall I really like it. But I have one important gripe with the internals tab: In my opinion the left panel feels a bit empty and devoid of information when it only shows the tissue types. In my opinion it could be better utilized by integrating some information about the metaballs into it instead of displaying these metaballs data in a pop-up menu.
As I understand it, this proposed metaball context menu would pop up in front of the organism. imo this is suboptimal as I think it would be better if you see the metaball you’re editing while doing so.

I therefore propose that the left panel includes a category called “segments” (I think this may be a more intuitive term for metaballs to use in-game). This category contains all the metaballs which the player can name to keep track of their function/position. As you can see, in my example the player has named them Head, Upper Abdomen, Lower Abdomen and so on.

Each segment section, when opened in the left panel, would include a list of that panels organs, as well as the tissue types which are contained within that segment but aren’t part of an organ.
The left panel functions much like a set of spoilers within spoilers which can be opened and closed as needed, much like many of our menus function. But there is an alternative way to quickly jump from segment menu to segment menu: Clicking on a segment of the organism will bring you straight to that segments menu and close all other segment menus.

Clicking on “Add Tissue Type” would send you to the top of the left panel where you can select a type to place in this segment from a library of all tissue types in the organism.
Clicking on one of the organs would open an organ pop-up window. This organ pop-up would open to the right, in front of the organism. This is consistent with the idea I layed out before: When you click on the metaball on the right side of the screen, the corresponding menu opens next to it, on the left side of the screen. When clicking on an organ on the left side of the screen, its corresponding menu opens next to it, on the right side of the screen.

I hope that I explained my suggestion as clearly as possible. I will sketch up a organ menu pop-up if needed. If I have time I may also do a simple animation of how clicking on a segment would open that segments menu and so on. Some of these things may be more easy to explain as a series of moving images rather than some rambling paragraphs.
(Btw @Heath I borrowed your critter for this concept muck-up, I hope that’s ok)


You raise a good point! Being able to avoid a popup menu would be nice as it clears up the player’s vision.

Using the left panel to display the statistics of the currently selected metaball is a pretty great idea, though I fear that listing all of the individual organ sets and such may end up feeling overly cluttered and messy.

I am personally in support of replacing the left menu with the selected part’s details whenever the user selects a part, but otherwise it would just display available tissues.

That being said, I am by no means an experienced graphics designer, so I’ll let the graphics team have the final say in the matter.

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Thanks for your reply! I think I get what you’re saying and I’m going to make an alternative mock-up which takes these changes into account. I may not fully understand what you mean by “organ sets”, but I’ll just go with my interpretation of what that means:)

I had this thought train about how we can deal with developing playstyles in the late-multicellular/Aware Stage. I think this stage will be Thrive’s cool “gig” in a way, considering there are no similar games representing player-controlled evolution in as scientific of a way as possible. It is also the stage of life where evolution will happen the most quickly and lead to the most diversity of playstyles, so it is important to get it down right.

There isn’t much of a concrete mechanic suggestion here; rather, it’s a suggestion on how we can think about things going forward.


We would be interested in representing the evolution of metazoans (animals) and plants in this part of the game. Given just how much diversity there is in the body-plans of macroscopic organisms, this is a vast undertaking. So we need to be deliberate and methodical in how we approach the implementation of various unique adaptations. If we’re too shallow with what we implement, then there will be very little replayability in Thrive and many shallow mechanics - if we’re too detailed in everything we implement, nothing will ever happen.

In my mind, the best way to address things is by looking at phylogenetic trees and focusing on a specific clade as we work through upgrades.

(skip this paragraph if you understand the diagram above) Just to review phylogenetic trees quickly in case anyone in the larger community reading this is rusty on them, they basically map out the evolutionary relationship between different groups of animals. The number of “splits” there are between different groups indicates how closely related they are. So in this diagram, you can see the line leading to Cnidaria (jellyfish & coral) and Ctenophora (comb jellies) indicates that Cnidaria and Ctenophora developed pretty early in the evolution of metazoans, splitting off from other metazoans very quickly. Here is a basic introduction to the topic: Phylogenetic Tree Basics - YouTube

As far as I’m aware, this particular image isn’t necessarily the “definitive” phylogenetic tree of metazoans - there are various phylogenetic trees online, with various levels of detail. The important thing though is that these diagrams present us with a clear understanding of how different animals relate to each other.

There are also phylogenetic trees for each group of metazoans. Here is a phylogenetic tree for Cnidarians…

So essentially, by looking at the larger eumetazoan phylogeny tree, we have the complete tree of life in our hands. So, what I think will work best is to focus on a specific part of the tree for a specific series of patches. We can determine what to focus on first based on how early in the evolutionary history of eumetazoans a specific group appears.

We obviously cannot represent every single species within a family, so our job will be determining what collection of cool adaptations will best represent the phylogeny of a specific clade, and then choosing a collection of cool traits from the various subphylum within said phylum to adequately represent a given species.

So for example, this can be how we breakdown the Cnidaria…


Cnidarians include Medusozoa, the group which includes all the” traditional” jellyfish and Anthozoa, which includes coral and other sessile organisms. We will likely want to focus most on Cubozoa and Scyphozoa (Medusozoans) to represent the two forms of major forms of jellyfish. We will also want to focus on coral, though they are more adequately represented by sessile gameplay and should be considered there.

Hydrozoans are the most numerous group of Cnidarians, though many are characterized by their tiny size (might not need many dedicated parts) and colonial nature (something we probably won’t simulate). There are also other forms of Medusozoans, though they are largely sessile, so there might be overlap with coral.

Medusozoa (Primarily Cubozoa and Scyphozoa)

Medusozoa tend to be motile, are radially symmetrical, and have nematocysts which allow them to sting. Some use their appendages to poison prey, though others have minimal predatory capacity and instead prefer filter-feeding using those appendages.

How to Represent Medusozoa

Their “floating” nature can be represented by allowing players to alter their mesoglea/buoyancy, and their stingers and tentacles can be represented by allowing players to develop appendages. Many of these appendages are like the familiar tentacles, though some are larger, expanding surface area.

How to Represent Scyphozoa

Scyphozoans are known as the “true jellyfish”. There are roughly 3 orders of scyphozoans, and perhaps up to 400 species. They tend to be larger than hydrozoans and contain a slightly more complex movement pattern which allows them to move at their size. Variance within Schyphozoa can focus on the presence or ratio of tentacles and oral arms. Some groups have many tentacles and no arms, some have arms and tentacles, others have no tentacles and only arms. Behavior variances also exist.

Thus, we can probably adequately represent Scyphozoans within Thrive by allowing variation in the number of tentacles and oral arms. Size will also naturally play a factor.

How to Represent Cubozoa

Cubozoans are box jellies. They are characterized by their potent toxicity and their more box-like shape. Cubozoans are known for having a rather complex nervous system and more capable sensory than other jellyfish. They can also swim pretty fast for jellyfish.

Thus, box jellies can be adequately represented in Thrive by allowing customization of the effects of jellyfish stingers (nematocysts). They will likely naturally emerge as players with Cnidarian-esque body plans enhance their nervous system and sensory capabilities.


Hydrozoans exhibit a good amount of diversity in the capability of their appendages. For example, some projectiles are merely grabbing/restraining rather than poisonous. That could be a relatively simple inclusion to diversify combat, akin to the toxin system in the Microbe Stage. They are also known to be rather small at times, though this can vary.

There are various types of sessile Medusozoans. These can be used to diversify sessile gameplay, though they aren’t necessary in my opinion.

Here we have a pretty simple way of representing an entire group of animals in Thrive with just these steps…

  1. Allow mesoglea and customization of buoyancy/density.
  2. Include appendages akin to oral arms and stinging nematocysts.
  3. Allow customization over the number of these appendages, the effects of these appendages, etc.
  4. Implement other global mechanics, like the evolution of sense and such.
  5. (Bonus) Implement some sessile gameplay capacities with Cnidarians.

That’s much more manageable than going through every single living jellyfish and throwing out some ideas, no? We can implement these and go on our merry way to represent other organisms.

I understand that doing this for every clade can look daunting, but we definitely can simplify things. For example, did you know that “worms” are represented across a huge variety of clades? There are mollusc worms, annelid worms, nematode worms, platyhelminthes worms, etc. Many shared traits exist between many groups of organisms, so we can oftentimes knock out various clades at the same time. Or atleast, be able to repackage various adaptations/mechanics for future traits. Jellyfish appendages can translate to octopi appendages eventually. It also helps to realize that players will have a lot of fun in combining various traits from various clades; we don’t have to necessarily think of things as being so specialized.

Of course, there are certain clades that will require a lot of focus. Vertebrates, Crustaceans, Molluscs, and Hexapoda as examples. But if nothing else, I think this approach to developing the macroscopic stages will be the best way to approach this daunting task from a design perspective:

  1. Research a clade. Familiarize yourself somewhat with the orders of said clade.
  2. Find out the defining traits of the clade and its various orders. There are many of course, but simplify your list to the least amount of traits for the most amount of diversity. Identify some traits which might be bonus objectives as well.
  3. Then, we start developing this group of animals, focusing on them for a series of updates.
  4. Once all “bottom-line” traits are implemented, repeat the cycle with a new clade.
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I think this is a great run-down of the process of accounting for potential variety in Thrive. Maybe I’ll post a link on our wiki page to this, or condense it into a paragraph to help prime new designers on finding inspiration for features.

That being said, we must be ever mindful of casting too wide a net when it comes to creature editing, lest players become rather overwhelmed.

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Hello all,

As I’ve been getting more motivation to get involved with Thrive again, I’ve been dumping some thought into this topic just to get the creative juices flowing. I wanted a rough idea of the macroscopic stages - more specifically, I wanted to create an outline of how we could go about representing the most number of organisms with the least number of features necessary. So to go about this endeavor, I read a bit into phylogeny and taxonomy, and tried to characterize various groups of organisms I noticed.

I have a clade-by-clade breakdown below, but first, I wanted to note some general thoughts I’ve had as I went about this exercise…

  1. Mechanics Over Parts - Thrive’s early macroscopic stages will likely be carried more by underlying mechanics shared by most organisms and less by unique “parts/traits” giving abilities relative to the later portion of the macroscopic stage. Before the arrival of the more complex vertebrates, arthropods, molluscs, and annelids, organisms were very weird structurally, but had relatively simple ecological niches. They were mostly filter-feeders, bottom-feeders, and very occasionally were limited predators. The first two niches will largely be influenced by fundamental mechanics, such as surface area-volume and organ systems. Furthermore, we want to make sure the player has a grasp of their basic macroscopic mechanics before throwing them to super-predators.
  2. Progression Pipelines - I think there will generally be two “game progression styles” in the early macroscopic/late multicellular stages, which I informally/affectionately nickname the “Thrivian Jelly Pipeline” and the “Thrivian Worm Pipeline”. The Thrivian Jelly Pipeline covers clades like that of the ctenophora and the cnidarians, while the “Worm Pipeline” covers everything else. The Jelly Pipeline is more limited in progression, as most advanced organisms evolved from worm-like organisms; as such, it’ll act as a unique playstyle. The worm pipeline is likely more standard to most Thrive playthroughs, and more directly proceeds to more advanced morphologies. The two aren’t necessarily mutually exclusive by the way, but the more Jelly-Like you are, the harder it is to evolve advanced structures in your body plan.
  3. Scope Limits - I think there are two things that we should declare not to incorporate within Thrive now unless implementation is very simple, and a third thing we should really think about. First, colonial macroscopic organisms, as these are a very niche and complex cases. Second, complex endoparasitic organisms, as it would be a nightmare to represent a microscopic representation of the inside of another organism. Third, we should really put some thought into the various scales we will represent. There will undoubtedly be times were we will have to cut between various “scales”, such as in microscopic multicellular organisms to the macroscopic world, and omit certain niches or organisms. Where will these cuts occur?

This post focuses on the “Thrivian Worm Pipeline”. I try to give a broad description of various clades, and infer some basic parts or mechanics we can implement into Thrive. As such, most of this will be focused on the early parts of the late-multicellular, probably before the playthrough’s “Cambrian Explosion” where more advanced morphologies appear.

By the end of this post, hopefully you guys understand what I mean, and hopefully we will have a slightly clear understanding of how we can define our scope for the early macroscopic stage.

Going through this has made me believe it is actually very feasible to represent a good amount of diversity with a large, but realistic amount of effort. I hope you guys emerge with the same feeling, and I promise that I will begin focusing on more immediate concepts soon again!



Xenacoelomorpha are triploblastic and bilateral, meaning they are able to develop muscle-derived and more specialized organ systems, and are bilaterally symmetrical. They do not have a complete digestive system (their mouth filters both food and waste because they don’t have an anus).

There are two major clades within Xenacoelomorpha…

  1. Acoelomorpha
  2. Xenoturbellida

Xenacoelomorpha probably serves as the representation of what most macroscopic animals in Thrive will look like only a bit before they start specializing into more unique organisms. They don’t really have any unique characteristics to implement.


Containing roughly 6 species within the same genus, Xenoturbellida represents a very small group of animals. I don’t think there is much we can derive from this clade. They notably have a mouth opening on the bottom of their body rather than on their anterior side. Above is a Xenoturbellida that looks like a churro; most Xenacoelomorpha look a lot like this, except less churro-esque.

Implications for Thrive

Churros. Having the ability to customize where a mouth part is placed would be an interesting characteristic for more simple organisms. However, if that interferes with the future parts of the multicellular stage with a more defined head and mouth at front of body, then that takes precedent.


There are roughly 350 Acoelomorpha, representing a decently-sized clade. Being rather small animals, most of them registering on the centimeter range, they generally live either planktonic lifestyles or slither around on the benthic floor. A few of them have very simple sensory organs called ocelli, among the simplest of metazoan eyes. Above are mint-sauce worms, an example of Acoelomorpha.

Notably, some Acoelomorpha are able to integrate photosynthetic plankton within their epidermis via consumption. This allows them to benefit from photosynthesis; some of these organisms depend completely on their symbionts.

Implications for Thrive

As said above, there likely isn’t much to extract from Acoelomorpha; they just serve as a representation of what most players will somewhat look like at some point in their playthrough.

A unique ability we can implement is to get some photosynthetic capability from the food you eat. This would have to be balanced in some way to make it so that only very simple organisms with very thin membranes can possibly benefit from this adaptation. For example, reducing temperature tolerance ranges and health could work.

So, I guess the breakdown for this group after simple mechanics are implemented involves…

  1. Implement a capacity for the player to absorb the photosynthetic ability of what they eat if they have sufficient adaptations. I would think this would be more of a bonus trait rather than a core requirement in terms of mechanics.


From here, we can discuss Spiralia, a large group of metazoans including some more complex organisms worthy of attention.

Platyhelminthes - The Flat Worms

The flatworms. Triploblastic and bilateral, flatworms have no true body cavity, resulting in a rather simple body plan. They display cephalization (they have a true head) and have a more developed nervous system, though they don’t have a complete digestive system. Their high surface area allows them to circumvent the need for a elaborate respiratory or circulatory system, relying mostly on their digestive system for circulation. Most are rather small (the millimeter range), though some are rather visible benthic animals. Their mouth notably is found near the bottom of their body, which looks somewhat like a proboscis. This mouth can extend in some species, though not to a significant amount.

There are two major groups of platyhelminthes: the Catenulida and the Rhabditophora. The Catenulida have been rather difficult for scientists to distinguish due to their relatively small number of species and their similar morphology; meanwhile, the Rhabditophora are the more “iconic” species of flatworms. Rhabditophora include the notorious tapeworm, and many other parasitic species.

Implications for Thrive

To me, the flatworms represent another point in the “basal worm pipeline” that most players will likely end up a part of as they become more advanced organisms. They represent a “step-up” in terms of Thrive progression, with the advent of a more advanced digestive and nervous system. I think organisms such as these will emerge naturally in Thrive without the need to implement unique mechanics, and thus, gameplay for these sorts of organisms will depend on the fundamental game mechanics shared by all macroscopic organisms. I notice that this is a trend with many of the most basal, early-multicellular organisms - so we might want to pay attention to creating simple, but fun mechanics for the early stages of the late-multicellular stage.

I will say though that flatworms can be very colorful, so having nice customization options could be seen as a bonus for this clade. And of course, being able to “flatten” the metaball body plan of soft-bodied organisms would help visually represent these organisms as well.

Nemerteans - the Ribbon/Proboscis Worms

Nemerteans uniquely have a proboscis. This projectile proboscis can rapidly extend, capturing prey items and increasing surface area. They are rather similar to flat worms - however, they have a complete digestive system (the presence of an anus) and a closed circulatory system, representing one of the most basal organisms to develop such features.

The two major groups of ribbon worms include the Enopla and the Anopla. The most distinguishing feature between these two groups revolve around the presence/absence of a “stylet” in their proboscis, which essentially is a sharp needle-like structure. Enopla have stylets; they sometimes utilize it to grasp prey.

Implications for Thrive: Another point in the Thrivian “worm-pipeline”, nemerteans can be adequately represented with what has been discussed above upon implementation of a proboscis…

  • Implement proboscis.
  • Allow customization of proboscis. An “unarmed” proboscis can completely consume small-enough prey, but is rather useless against larger organisms. An armed proboscis can grab and inflict damage on larger prey items, but does less damage.
  • Armed proboscis can be imbued with toxins.

Gnathifera - Jawed Worms

A larger clade rather than a phylum, this group contains many smaller clades. I think it’s worthwhile to discuss these organisms as a whole before individual diving in. Gnathifera all display various forms of chitin-derived mandibles. These mandibles come in various forms and perform various functions. As such, the most basal feature which can represent the jawed worms in Thrive is…

  • Implement simple, chitinous mandibles as a very basal jaw structure.

Diving into each individual phylum of the Gnathifera will help us see some customization options for these jaws. We can’t really go into much depth here without a larger discussion of how mandible customization will work however, so this will likely be a rather brief section.

Chaetognatha - Arrow Worms (Gnathifera)

Placement of these organisms is a bit dubious within Spiralia, but these organisms represent a large percentage of planktonic biomass despite a relatively small number of species. These are very active predators, using their mandibles to prey on smaller organisms. They appear to be a very ancient bilateral phylum.

Arrow worms notably have bristle-like fins on the side of their body which lets them rapidly accelerate, though they do not have endurance. Many of them utilize the same toxins utilized by pufferfish in their bites. Arrow worm mandibles can likely be implemented with dedicated mandible customization. Implementing toxin capabilities to these basic mandibles should cover the rest.

  • Implementing mandible customization. This would likely represent the advent of the arthropod-esque playstyle in Thrive, so it is a needed feature anyways.

  • Implement basic fin customization for basal body plans. A lot of the uniqueness of the fins of arrow worms is their “cosmetic uniqueness”, so if it’s too hard to graphically represent such a feature without labor, it’ll worthwhile to skip.

Gnathostomulida - Lesser Jaw Worms (Gnathifera)

Gnathostomulida were recognized as an individual clade in the late 1960’s. They are a rather small group of organisms, and are also small in physical size. I don’t these organisms require a unique mechanism to be represented in Thrive as long as other fundamental systems are implemented. If anything can be jotted down…

  • Jaw customization feature which allows organisms to “scrape” organic material off the ocean floor. There have been prior discussions about this, as this will serve as one of the first methods of gathering food available, so this should be implicit to the late-multicellular stage itself.

Rotifera - Wheel Jaws (Gnathifera)

Among the most numerous organisms on today’s Earth, Rotifera are most known for their jaws, which allow suction akin to cilia in Thrive.

Most rotifers are tiny, meaning their suction ability might not be adequately represented in Thrive at the macroscopic level if we must concede some scales of detail. As such, it might not be worth discussing this clade currently.

Brachiopoda - Asymmetrical Clams

Will not cover now; sessile gameplay and unique feature (clams)

Phoronida - Sessile Filter-Feeding Worms

Will not cover now; sessile gameplay

Bryozoa (Ento & Ectoprocta) - Colonial Filter Feeders

Will not cover; colonial gameplay probably outside scope of Thrive

Annelids - Segmented Worms on Crack

The annelids are an incredibly large and diverse group of animals known for their segmentation and relatively complex organ structures. They include leeches, earthworms, beard worms, and many other organisms. All are soft-bodied and have a complete digestive system, as well as a pair of nerves running throughout their body. They all have closed circulatory systems and features analogous to hearts.

Most annelids have setae, which are essentially tiny extensions throughout the skin of the organism. In some marine annelids, setae can look a lot like limbs, allowing benthic dwelling. For other annelids, such as the earthworms, setae are miniscule and assist with digging. Most annelids are detrivores, though some display predation and more active dietary habits.

I think annelids can largely be represented in Thrive as being the final, most complex form in the Thrivian “worm-pipeline”. Annelids have many diverse functions and forms, so allowing players creativity in customization their soft-bodied, wormlike organisms is the best way to approach this clade of organisms without killing ourselves.

It’ll be worthwhile to address annelids phylum by phylum, but here are some traits ubiquitous to most that can help distinguish annelid-like organisms from other Thrivian organisms. A lot of what distinguishes annelid phylums from other phylums are variations in the below features anyways:

  • Segmentation. This will likely be a fundamental editor mechanic for soft-bodied and arthropodic organisms which distinguishes them from vertebrates.
  • Setae, which can assist with burrowing or act like legs. Perhaps setae can be the simplest and first available limbs.

Polychaeta - A somewhat dubious grouping of largely marine segmented worms that are known for their distinguishable setae protrusions. Include the sandworms, bobbit worms, sea mice, and many other notable annelids.

  • Because these organisms are very diverse, allowing decent setae customization is probably the best way to represent them. Some setae can be longer and have greater surface area, allowing swimming. Other setae can be shorter and can allow for crawling or burrowing. Other setae can have poison on them, and can serve as a defense mechanism.
  • Several unique organisms here have features which overlap with other groups of organisms, such as jaws and burrowing.

Oligochaeta - A somewhat old-school grouping of Naididae, Aeolosomatidae, and Lumbricidae. Aeolosomatidae and Naididae are microscopic, and are outside of the scope of this document for now. Lumbricidae include 6000 species of earth-worms. This group of organisms will likely be represented in the switch to land. They depend on a mucous layer, as well as damper conditions, to remain moist.

  • This group would likely be represented only when movement to land is implemented, which is in the distant future.

Hirudinea - The leeches. Implications for this group are pretty obvious, and will likely be the most defined and feasible “parasitic” niche in Thrive.

  • Implementing an ability for simple jaws and proboscis to have a parasitic ability, allowing hostile resource transfer but minimizing opportunity to consume organic matter whole.

Annelids are honestly an entire beast of a clade to tackle, and will likely deserve their own post later similar to the other more complex organisms in the multicellular/aware stages. However, this provides a general overview that gives us rough ideas. I still stand by my statement that annelids represent the “pinnacle” of the Thrivian worm pipeline.




Will not cover now due to microscopic scale. If nothing else, nematodes will likely serve to be microscopic food for filter-feeders and bottom-feeders.


Will not cover now due to microscopic scale.


Will not cover. Endo-parasitic nature likely outside of the scope of Thrive.


Also known as mud dragons, this group of animals will likely be represented by the fundamental mechanics of the late-multicellular and aware stages. They are known to be able to burrow.

Look at that; in what we covered, we have addressed a great deal of metazoan diversity already! Here is a list of all features covered.


  • Surface-Area to Volume Ratio - This will be a very definitive feature of the early macroscopic stages, defining filter-feeding and buoyancy for organisms which do not have much morphological complexity. It will also directly feed into the metabolism of organisms, having direct influence on circulation, digestion, and respiration. Will become less important as organisms develop more advanced and thick skins, though will always have an effect. Individual discussion.
  • Organ System - The fundamental feature shared by all organisms. Will most correlate to progression, and will serve as the basis of metabolism for organisms. The late-multicellular stage will represent the advent and acquisition of initial organ parts, allowing players to get familiar with the system as a whole.
  • Mesoglea - Representing Cnidarians and Ctenophora, this will represent an immediate way for organisms to increase buoyancy and float, but will make it difficult to evolve advanced organ or membrane structures.
  • Nematocyst/Celloblast Appendages and Customization - Representing Cnidarian and Ctenophoran appendages. Have limited control and advancement, but allow for basic grappling, filter-feeding, and stinging.
  • Surface-Area/Volume Increasing Appendages - This appendages will be simple ways to increase surface area or volume, thereby increasing specific characteristics. Will be especially important in the early macroscopic stages, but less important as SA:V becomes less important. Will provide customization and flair options.
  • Easy Access to Bilateral Body-Plan - This will represent the “worm” body plan, and will be the basal body plan for more complex organisms. Probably a discussion of how the editor will look in general.
  • Burrowing - An important feature for more advanced playstyles. Should probably be discussed later.
  • Proboscis and Customization - Probably the simplest mouth part to be offered to the player. Allows for bottom-feeding, as well as some hostile resource transfer, filter-feeding, and limited predation
  • Basal Mandible/Mouth Customization - Requires its own discussion later in all likelihood.
  • Basic Fin Appendages - Requires its own discussion later in all likelihood.
  • Segmentation - As discussed in earlier posts, segmentation would likely be represented as an inherent part of the body plan/metaball editor. For certain organisms, players can group metaballs together to form a “segment”, which will be important for arthropods especially. Likely requires its own discussion, though mechanisms wouldn’t be that influential in soft-bodied organisms and basically non-existent in vertebrates.
  • Setae And Customization - Represent more advanced limbs with diverse functions, allowing swimming, crawling, and digging.
  • Bioluminescence - A notable feature of various worm-like organisms.

Doesn’t sound too bad when put like this, right? A lot of organisms can probably be represented with a combination of various organisms if we offer a decent amount of customization.

Images are important, but I didn’t want to spam them throughout the entire post as that could hurt readability. Here are images of various organisms.


Scyphozoa (Cnidaria)

Cubozoa (Cnidaria)

Hydrozoa (Cnidaria)

Xenoturbellida (Xenacoelomorpha)

Acoelomorpha (Xenacoelomorpha)

Platyhelminthes - The Flat Worms

Nemerteans - the Ribbon/Proboscis Worms

Chaetognatha - Arrow Worms (Gnathifera)

Gnathostomulida - Lesser Jaw Worms (Gnathifera)

Polychaeta (Annelids)



These organisms didn’t have a description for various reasons, but I’ll list them here still.

Brachiopoda - Asymmetrical Clams

Phoronida - Sessile Filter-Feeding Worms

Bryozoa (Ento & Ectoprocta) - Colonial Filter Feeders

Rotifera - Wheel Jaws (Gnathifera)




Very evocative and sensible post. It does a good job of not making the early multicellular stage seem like an impossible thing to implement, but rather like a huge but doable task.
Since gameplay at various scales is one of the principle topics regarding the 3D stages from a graphical perspective, I wanted to ask you some more about these statements:

Which scales would you have in mind when thinking about scales which can possibly be omitted? Are you mainly thinking about a jump in scale that happens immediately after the 2D-3D transition or do you think there are other gaps afterwards which you would consider?
Personally, I’m in favor of making the transitions from scale to scale as smooth as possible. But I’m aware that this will be an issue which will be determined to a large extent by the technical possibilities.
I’m inviting you all to branch out the discussion about the technical and graphical aspects of this consideration of scale into this thread:
This way we can keep the discussion in this thread more focused on the editor and organ progression.

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