Macroscopic Editor, Progression, and Principles

I wanted to make a post which compiled my previous posts and will serve as a place for future concepts related to how we deal with the macroscopic editor since I feel like they’re some of the more detailed concepts we have in that area. I notice I find myself zooming around the forums to find material on this, so hopefully this post will centralize that discussion a bit.

I’d also like to note now that these discussions don’t really have a bearing on @hhyyrylainen’s work for the prototypes because those are meant to be proof of concepts and baselines more than actual complete stages. These concepts require much more discussion and detail to actually pull off, and would definitely require a whole lot of work in an area of the game that we aren’t really focused on at this moment. So I wanted to make that distinction now.

Discussion related to the 3D editor are spread out all across the place…

But there isn’t much content focused on detailing how the editor will holistically offer the flexibility for players to create various types of body plans, and how the editor will progress with the evolution of morphological complexity (in other words, how progression will work with morphology). So, I want to collect my two posts, contextualize them, list out gaps in my existing concepts, and give indication of where we can go next. Note that not every idea in those posts are mine; there are a few ideas that have been established since 2012, and Buckly has created a pretty-slick concept for the editor UI (seen in the above links).

This is all far enough from the current moment that we don’t need to know exactly what we are going to do right now, but we definitely should have a rough idea of how things can be dealt with so that we aren’t hastily putting together concepts when we realize we are fast approaching a completed 2D stage. We don’t need a concentrated effort yet, but we should atleast have a centralized area of discussion so that we can understand where we are at and so that we know what areas are still murky.

First, I will discuss some general principles I have behind my thoughts regarding this topic…

Go From the Broadest to Most Specific Level of Complexity, not Other Way Around - We should establish how the broadest level of detail in an organism should work first before going more detailed rather than starting at a very specific level of detail and then going up.

To be more clear and explicit: I notice that we oftentimes approach the macroscopic editor by first thinking of designing the specific cell types that are featured in said macroscopic organism. The traditional Thrive line of thought was design the cell, turn that into tissue, and sculpt that tissue into a larger organism. But I really worry about this approach for many reasons…

  1. Tissue types are very interconnected and intertwined. A blood vessel is in a muscle tissue, which is laid on top of bones which have a very stiff outer layer of tissue and a very soft layer of internal tissue, and all that is under skin tissue. Of course, if we took this approach, we wouldn’t have this layer of complexity. But it reinforces how messy things can become. What if you want to replace a specific tissue type? What if you want to extend a bone but don’t have enough MP to extend the muscle and skin layers? How would the player be able to design a decent looking creature? It could all end up being a very lumpy and incoherent mess.
  2. There is an endless amount of organelles and adaptations we would implement if we wanted to go into a meaningful amount of replayability and diversity. The human body has atleast 200 types of cells (How Many Cells Are in the Human Body? Types, Production, Loss, More), with various specialized cells involved in the same organ and organ systems. We wouldn’t have this number of different cells be necessary of course, but the amount of unique adaptations, progression, and effort that would have to be put into even 50 different types of cells would be migraine inducing. And that would again lead to questions similar to those mentioned in the above point. For example, how could there be enough MP points to allow a player to design a cell then make a meaningful structure out of these cells? How will the player know which tissue needs to be upgraded? How would we limit progression and balance the game with this amount of detail? We could have it so that a player picks from a very few parts to define what a specific tissue type may be, but without an underlying system assisting this process, that would also lead to a lot of difficulties.
  3. If excessively burdensome, this system will likely take away focus from parts of the macroscopic editor that the player will have a very explicit interest in. I’m not 100% sure about this, but I think players will mostly be focused on broader details and more externally functioning parts, like limbs, rather than the tiniest specifics of their organs. The macroscopic stage will be all about interactions with other organisms and exploring the 3D environment, so we don’t want to bog the player down with too much micromanagement. Organs and organ systems will likely be used to define the behavior of an organism - what food it likes, its level of activity, its personality, preferred habitat, and certain unique abilities - so we don’t want to make the player think about every single component of their organism’s innards.

Considering all this, we should approach the question of the macroscopic editor through addressing the broad details of structure and body-plans first before diving into the details. The thoughts above were not arguing against the complete exclusion of editing very fine details in your organism - if properly done, it could heavily boost replayability and creativity in the macroscopic stage. Rather, I was making the point that approaching things by trying to think of how various incredibly detailed and distant systems could intertwine to create an incredibly complex macroscopic organism would result in a lot of pain.

The above principle has strong implications for the future of Thrive. For example, this probably means that we will address organ systems as a whole first before addressing specific organs. Instead of making the player create a digestive system by telling them to glue together a stomach, intestine, mouth opening, and anal opening, we will probably give the player a very basic digestive tract first and then allow the development of organs to operate almost as upgrades and specializations. The same principle will be applied to other parts of the game. We won’t make the player develop a endoskeleton piece by piece from scratch but will probably give them a notochord and use that as the base for developing other advanced parts. We won’t make the player deal with the circulatory system by making them coordinate various pumps and channels, but will give a basic circulation and will allow the player to tweak this circulation. The list goes on and on.

Be Mindful of Body-Plan Diversity - Many existing concepts address how morphology for organisms with an endoskeleton will work, but the majority of complex life either is soft-bodied, exoskeleton-based, or otherwise not bound to an internal skeleton, like plants. We should be mindful of this diversity.

With that discussed, I will now briefly summarize the two posts I have already shared. If you’ve already read my two previous posts on the topic, this is just compressing that information. So you can skip this section.


How will we deal with the huge transitions in the evolution macroscopic body plans?

Based on the above post, which has more detail and sources.

This addresses various areas…

  1. Dealing with the broadest levels of progression seen in metazoans
  2. Providing a basic understanding of how we will address some of the broadest level of details by shifting focus to body plans
  3. Providing the most basic tools for implementing change in body plans and organ systems

The topic of germ layers and the topic of embryology as a whole have been frontiers in developing our understanding of phylogeny and evolution over the past few decades. When experts refer to “true” mutlicellular organisms, they are referring to the presence of a germ layer in an organism.

Germ layers are most commonly used in the context of embryo development. They refer to one of three layers of cells in an embryo, and are important because each of these layers specializes into different types of cells. These are…

  • Ectoderm - The outer layer, differentiates most notably into the skin and nervous system of an organism
  • Mesoderm - The middle layer, differentiating into bones, various specialized muscles such as blood vessels and skeletal muscles. Interacts with other layers to produce more complex structures
  • Endoderm - the innermost layer, differentiating into the gastrointestinal and respiratory system.

Sponges represent the only well-known metazoans that have no germ layers. Diploblastic organisms include comb jellies, jellyfish, and coral; the rest of the metazoans, including flatworms, arthropods, mollusks, and vertebrates are triploblastic. Triploblasty originates from diploblasty, and so on.

Gameplay wise, we can use the concept of germ layers to organize how progression as a whole can work, informing us on the various tools we need to offer to the player at various stages of complexity to make various forms of life.

The player developing a GI tract will serve as the advent of the complex macroscopic editor and the advent of the 3D editor and germ layers. Upon developing it, the editor will change from the familiar Structure - Membrane - Behavior organization to the macroscopic Structure - Body Plan - Behavior editor. Structure parts will change to become more macroscopic.

The Body Plan tab will deal with widespread, generalized changes to your organism’s germ layers. Things like changing the type of GI tract between a complete and incomplete system, instructing the development of an organ, changing lysosome composition, and other generalized features will be found here. So this concept proposes that organs are dealt with less through structure and more through body plan, which might be a bit different from what we are used to. I’m not particularly hellbent on this, but I think it helps to have organs composing a system under the same region in the editor.

Initially, the player will be diploblastic, having the ectodermal and endodermal tissue layers. The ectoderm provides tools for the player to deal with their skin, while the endoderm will provide tools for the player to deal with their basic respiratory and digestive tract.

The ectoderm will act vaguely like the prior membrane tab, allowing the player to shift between various outer layers. Single and double membrane layers will serve as “basic” uncovered skin (single membranes aren’t found in macroscopic organisms as far as I am aware, so this needs some thought beforehand). Cellulose will represent a plant-like build (sessile organisms will be addressed separately). Chitin, carbonate, and silicia will represent the various types of exoskeletons/outer-casings. Though it is important to note that silicia is oftentimes used only by unicellular or sessile organisms, and calcium carbonate is similarly used or is mixed in small concentrations with chitinous membranes, so we might need to restructure how we think about membranes.

The endoderm will serve as the basis of the respiratory tract and digestive system. Here are some of my previous thoughts since I can’t think of a way to simplify them:

some limited customization options will be present already in diploblastic organisms. For example, the digestive tract can allow customization of diet based on membrane, and can be customized to allow more storage and somehow correspond to digestive efficiency (how quickly you extract energy from food in your gut). Perhaps more storage means less efficiency while less storage means more efficiency? There can be many ways of dealing with this.

The basal respiratory system can have a slider related to oxygen-intake efficiency. Higher oxygen-intake efficiency gives you more energy quickly but burns through your energy source quicker, meaning you’ll need to be more ravenous, and also meaning your organism doesn’t do well in low-oxygen settings, such as the deeper ocean. Slower oxygen-intake efficiency gives you less energy but burns through your energy source slower, meaning you’ll have slower metabolism while also perhaps allowing you to live in the ocean depths.

As a diploblastic organism, you won’t have access to the mesoderm. Instead, you can determine the amount of “mesoglea” within your organism. More here…

The mesoderm will of course be missing at first in diploblastic organisms. Until then, the area in between the endoderm and ectoderm will be filled by mesoglea - the gelatinous material found in Cnidaria and Porifera which can be composed of both acellular and cellular material (question for theorists: is mesoglea assumed to be basal for all diploblastic animals or is it a unique adaptation to certain diploblasts?). A lack of mesoderm means the player will have limited options in regards to functionality drawn from mesoglea. However, one important function can be related to the organism’s density, and thus, whether your diploblastic animal drifts or crawls on the ocean floor: the more mesoglea, the less energy your organism needs to float above the surface of the water. As such, we can have a slider denoting the amount of mesoglea in your organism for now - more mesoglea means a lighter, more floaty organism akin to jellyfish, more agile and nimble yet more vulnerable to currents and with less health, while less mesoglea means a denser, more durable benthic organism with limited ability to get off the ocean floor.

The broader point is that we can address large changes to an organism’s composition through the body plan, and we can organize certain aspects of an organism’s body plan by grouping things into the endoderm, mesoderm, and ectoderm. And we can limit progression in these sections by emphasizing how important triploblasty is for the appearance of complex organs, with a lot of the more detailed components like a heart, large intestine, etc. being locked behind the mesoderm.

Note: The pop-up bubble next to “Type: Incomplete Digestive System” reads “Your digestive tract has only one opening, it being your mouth. Both food and waste go through this opening, reducing overall efficiency. Develop your digestive system further to create an anal opening and increase efficiency.”

Apologies for the hard to read text, but here is a basic concept of important information for the endoderm organized in the body plan tab. We ideally would want to use icons a lot more with a few expandable tabs for specific parts, perhaps in a way similar to the “Modify” UI layout concept. But I just listed some generic customization options I thought up of in 5 minutes.

My original concept had diploblasty (and thus the GI tract) developing when you click the “become macroscopic button”, This is a pretty broad jump, so we should think of a way to offer the development of diploblasty that isn’t such an abrupt change, meaning single germ-layer macroscopic organisms should be shown a bit of love. This would allow organisms like sponges to exist in Thrive. Regardless, we should offer diploblasty pretty quickly once the player becomes 3D, meaning whatever time before that would be pretty short with limited gameplay options (as is seen in really life really).


How will we represent the various diverse skeletal (and non-skeletal) structures which anchor an organism’s entire being?

Based on the above post, which has more detail and sources.

This concept addresses these areas…

  1. Provides a backbone for addressing the various types of morphology which don’t have an endoskeleton
  2. Provides a brief overview of how gameplay and the editor will slightly differ depending on your chosen skeletal system

We oftentimes think of how the editor will work for organisms who are like us - who have an internal skeleton. But to call ourselves a self-respecting all-encompassing evolution simulator, we definitely need to address hydrostatic (soft-bodied) and exoskeletons as well.

I would like to clarify something before diving in, however. I use the term “initial limb investment” in this, and all that means is the amount of MP it costs to create the first section of a limb. “Editing a limb” means adding onto this first section. So if a creature has a high initial limb investment with cheap limb editing, that means it costs a lot of MP to place down the beginning of this limb, but it doesn’t cost that much MP to add on to this limb. It’s a general term that has popped up in discussions on this topic all across the place, so I wanted to make sure it was clarified atleast somewhere if it wasn’t specifically addressed before.

A lot of this is copy and pasted from the listed post, so if you already read it, there isn’t much new here. You can also find an extensive list of the pros and cons for each body plan system in the original concept post, which I think is rather insightful.

Hydrostatic Skeletons (Diploblastic or Triploblastic Basal Structure)
The first skeletal structure to arise, a hydrostatic skeleton is shaped by a fluid-filled opening (coelom) within an organism. It essentially means that an organism doesn’t rely on a hard, bone-like structure to create its shape, and is soft-bodied. Molluscs, jellyfish, comb-jellies, most worms, and the vast majority of animals are soft-bodied.

Editing the Torso - Soft-bodied organism metaballs will probably operate a lot like vertebrate metaballs, but will have a lot more freedom in terms of playing with the properties of each metaball. To clarify more, remember how in Spore, increasing the size of a certain metaball along the spine would also make other metaballs increase in size a bit? For soft-bodied organisms, that effect will be a bit less emphasized so that one metaball will have less of an effect on another. This will allow more creativity with shapes.

Editing Limbs - One unique thing with soft-bodied organisms I think would be cool to see reflected in game, while also giving them a unique trait for the player to play around with, is for the ability for the anterior side of the creature to not necessarily be where its mouth is. I’m thinking of jellyfish and octopi in particular. Perhaps we can attach an ability for soft-bodied limbs to move backwards rather than forwards?

Regardless, the initial investment for limbs for soft-bodied organisms should be rather inexpensive, but modifications for these limbs should be somewhat expensive.

Exoskeletons (Triploblastic Chitinous Structure)
Editing the Torso - Each metaball within the torso represents a segment. To make a certain segment larger than another, the player can highlight specific metaballs and designate them as a group, which will serve an aesthetic purpose (what functional purpose should we attach?). For example, a player who wants to make a millipede like organism wouldn’t want to group any metaball together, while a player who wants to make an insect-like organism would want to group metaballs into 3 groups representing the thorax, head, and abdomen.

The segment with the mouth opening within it will be considered the head segment, and the segment with the anus opening within it would be considered the posterior.

Editing Limbs - Limbs should be rather easy to add for organisms with an exoskeleton, with both the initial investment for the joint and the modification of joints being rather inexpensive.

Concepts to illustrate segmentation. Note that different color metaballs belong to different segment groups. So for the centipede, each metaball is its own segment, for the ant, metaballs are split into three segment groups, etc.

Endoskeletons (Triploblastic Bone Structure)

Editing the Torso - This will probably be rather similar to Spore’s editor, so as of now I don’t think it needs too much explanation. Each metaball within the torso represents a vertebrae along the organism’s spine. You can manipulate each vertebrae to define your organism’s shape.

Editing Limbs - Limbs will be the costliest for organisms with endoskeletons, with both the initial limb investment and limb modifications being expensive. I think we should make the player specify where they would like to place a joint alongside the spinal cord instead of just having limbs be free dragging akin to Spore, although I am not too adamant about this of course. Once the player specifies this, a single jointed appendage can be placed. From there, players can add additional limb segments.

And that sums up my past two posts.


The above concepts present an interpretation of the macroscopic editor which presents methods to limit progression, addresses broad questions of how various organ systems will progress and be demonstrated to the player, and how the player will be able to make dramatic changes to their body plans in a cohesive way to create the organism they want to create. But there are gaps that we must address to officially say that we have a basic comprehensive plan for dealing with the macroscopic editor as a whole.

We need to understand how we will deal with the “unlocking” of diploblasty and triploblasty. Will it be a button? Will we somehow be measuring player complexity and then offer them upgrades once they meet certain thresholds? Will the player have to evolve certain systems to officially reach the next level of complexity? And where will the jump from 2D to 3D officially take place? Should we keep it as it is now, where you must reach 20 cells to jump to becoming macroscopic? I’d again like to point out that these concepts assume a jump over the sponge “level of complexity” directly towards animals like jellyfish and ctenaphores.

We also need to fully detail how limbs and extending the torso will work. This is pretty easy since previous concepts exist here. Limbs are largely settled I’d argue with the only questions being related to specific modifications such as adding graspers, stingers, etc., but we need to make sure that we accommodate for the different types of body plan structure (exoskeletons and hydrostatic skeletons). We will also need to figure out how to deal with size, which is also pretty easy; we should just limit the total amount of size a player is able to add onto their organism per session so that they don’t just go from a shrimp to a whale in a generation, and we should make osmoregulation costs scale differently depending on their organ systems and skeletal structure.

We need to research the various unique organs found within each organ system (and different types of organ systems as a whole in fact) across the animal kingdom to offer a diversity of options to the player, and then provide customization/modification options for these parts. I predict that we probably won’t have a huge number of explicitly different organs, but we probably will have to offer decently-extensive customization options; both goldfish and cows have stomachs, but a cow’s stomach looks very different from a goldfish’s. We also need a basic understanding of how and where specific organs developed to understand the evolutionary pressures behind them - insects don’t have stomachs because they aren’t big enough to need anything much bigger than a gut, for example.

And shells which don’t explicitly act as an exoskeleton, such as with molluscs and snails, need to be dealt with.

So I think that we have a clear understanding of how the broadest level of macroscopic editing can work (if these concepts are accepted, of course). Now, we go down a level, making things more specific. Perhaps we can find a way to include cell-editing at the end of all this.

I’ll likely be addressing a rudimentary way of dealing with organ customization and development based on the above principles. I feel like a general understanding of that can give us a better understanding of how progression in the first few moments of the late-multicellular stage will work. From there, I’m sure things will snowball.


Good initiative with making this thread. I think several important questions are raised. A big one is, where do we draw the line with the level of detail. Like for example, how many of the mutations will be done at the microscopic level instead of at the macroscopic level.

Obviously something like modifying the skeleton or placing bones is macroscopic. But what about changing what the stomach is able to digest. Do we do that macroscopically by just letting the player select the stomach and access a menu where he can evolve what to be able to digest? Or do we have the player zoom into the Microbe Editor and evolve the actual lysosomes of the stomach’s cells? And if we have the player zoom into the Microbe Editor for editing the stomach, how many other places do we allow that? Because I worry if we allow that too much a simple trip to the editor will require a lot of work and become a chore for the player. We should ideally balance level of detail with also making editor trips as quick and efficient as possible, so that the player can relatively easily and quickly design their creature the way they want.

One thing I would like to point out though is that I don’t think we should tie germ layers into the Organism Editor concepts. While Germ Layers are definitely cool to learn about and tell us a lot about the evolution of animals on Earth, I don’t see anything in their study that is broadly applicable to life on other planets. As far as I know there’s no reason to believe life on other planets will evolve only 2-3 germ layers, or that they will evolve to have the same organs derive from the same layers. For example, our Deuterostome ancestors on earth evolved a throughgut from their endoderm, partially because it was one of their first evolutions and it’s likely the mesoderm didn’t even exist at that time. But who knows whether in another situation, the throughgut would have evolved from the ectoderm, or the mesoderm, or if a fourth layer would have evolved and it would have derived from that. What’s more, some of these organ systems have pieces derived from several different germ layers (like the digestive tract is mostly endoderm but then the spleen is mesoderm), which can make the overall pattern messy. Overall it seems like the study of germ layers is a cool observation of how life evolved on Earth, but does not provide a set of rules for how life should evolve elsewhere.

EDIT: Got to go but wanted to add that I agree with basically everything on the latter half of using metaballs to structure organisms. Those are also handy visuals to help visualize the process. We could definitely use more concept art to visualize the Organism Editor.

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I think I’m talking about different things when I say “tissue type” than what other people understand. So I’ll try to clarify that first.

In my prototypes tissue types are more like archtypes or base stat giving things rather than trying to map to the 200 cell types that are in humans. So my idea is that the player would have just a few different tissue types they made in early multicellular that would be mapped to late multicellular. These would affect how touch the player creature’s skin is and how much resources it costs to make and upkeep. Then there would be a few specialized tissue types (marked by placing some unique organelle in them) that mark things like the brain or different muscle types (so when making a joint the player would be given a list of muscle types to choose from).

I think my understanding of tissue types maps pretty closely to what you mean by going starting from a broad level of detail.

My main criticism of the germ layers is that it seems just so complex to me in terms of how hard it is to implement and how hard it would be to make it easy to control.

Here’s my take on the whole editor: we should split it into two:

  • One for structure. This would use the metaball editor, I think players will be able to intuitively understand how to place and shift balls around to make their overall shape
  • Internal organs editor which would deal with all of the complexity with cell types and organ systems you lined out being problematic

In the initial implementation I’m purely focusing on the first point so that internal organs are just assumed to be present.

While we seem to approach this differently, it looks like Nick agrees with me that germ layers shouldn’t be the primary focus on how we would build out the macroscopic editor.

So I tried to make a visualisation for this germ-layer-based „Body Plan“ tab.
hh and Nick have brought forth some valid concerns regarding the prominence of the germ layer system while I was drawing this out. So when I have time I‘m going to make an alternative piece of concept art which goes with hhs proposed „Internal Organs“ tab instead of the germ layers.

Note that my concept art includes a proposition of how to easily and intuitively integrate hhs plan of having the tissue types be based on the cells. As hh said, we don‘t have to go crazy with different cell types, their specialisations and relative placement to one another.
In my proposition, the Body Plan tab is essentially the continuation of the Structure Tab in the early 2D multicellular stage. The tissue types correspond to the cell types which you have evolved before. The only difference is that you can now control their relative concentration within the germ layer with a slider (the colorful one below composition).

One thing I like with this germ layer approach is that it lends itself well to an intuitive organisation of the editor tab. Note that the editor tabs layout follows the layout of the body plan: The outermost germ layer is on top, the innermost layer would be on the bottom.

Edit: Here is how i would look for a diploblastic organism:

Note that the endoderm has a completely different interface than the ectoderm. This is because the ectoderm and endoderm are for internal organs while the ectodem is for changing the properties of the skin, als well as for „exporting“ cell types to the Structure tab where they can be used for external organs like horns or eyes.

Also note that „Add Germ Layer“ is in between the ectoderm and endoderm, as the mesoderm would be evolved in between the other two layers. This is what I was talking about earlier regarding the vertical layout of the tab reflecting the layout of the organism from outermost to innermost.

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Sorry for the doublepost, but I feel like this is necessary since this piece is based on hhs idea of an ‚Internal Organs‘ tab and, in contrast to my other pieces, ignores the germ layers completely.

I shortened the tabs name to ‚Internal‘ since a) it fits better into the header and b) it‘s more accurate as the tab also encompasses internal structures which aren‘t organs like the mesoglea.

Note that the organ has a section called ‚connected to‘. This way we can properly determine which organs are connected to one another and to which orifices/openings if any.
I imagine that orifices would be placed in the ‚external‘ tab, just like other external structures.
This system of connecting organs and placing orifices doesn‘t have to be implemented in the prototype, it‘s for later down the road. It‘s also just a suggestion, so feel free to rebuke it or make counter-suggestions.

For a while I was quiet on board with the whole germ layer idea, but when comparing my visualisations now, I prefer hhs approach. The split into ‚External‘ and ‚Internal‘ is much more understandable than the split into ‚Structure‘ and ‚Body Plan‘. The germ layers also add a level of organisation above the organs which is just more visual clutter within the tab.

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You got close, but this is what it looks like in game right now:

The tab says “internals”

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I still wonder how much gameplay could meaningfully be abstracted from a system like this, but that does sound better, especially if we limit this feature to a few cell types. I think we would need to make sure to limit cell-editing to a few parts, such as the stomach or skin as you mention. But I still have concerns because for many organs, a lot of their functions are very difficult to describe by only zooming in to individual cells; it’s oftentimes how each cell connects and the shape of the organ itself which can make really dramatic differences. I’m thinking of the fact that the stomach is essentially a bag where cells eject acid then externally digest whatever is in said bag. We could have a lot of this be dealt with the macroscopic organ-editing tools, but then I wonder if cellular editing for the stomach would basically just be going in and tweaking a lysosome, which could more easily be represented without the need for a cellular editor. I’m sure we could think up of more ideas however.

It’s a fair point. I definitely haven’t demonstrated this because I just rambled about it for 10 paragraphs in my main post, but we don’t need to explicitly break up the editor into “mesoderm” and “endoderm” and the such. We can break up the editor into more accessible and intuitive sections than “body plan” and “structure”, and “internal” and “external” is a good idea.

I think we just have to be mindful of germ layers as we approach progression throughout the multicellular stage because it is a huge chunk of our understanding of evolutionary history. There are certain gaps metazoans have broken through which fundamentally changed the rules of internal and external structure, and much of that is related to the development of germ layers. Ultimately, I think if we just make sure that advanced muscles, bones, and organs aren’t offered immediately in the macroscopic stage, meaning the player has to get their basal digestive and respiratory tract in order first, we’d essentially be implicitly mirroring germ layers without having to explicitly mention them. I think this intuitively slides into the macroscopic stage since we don’t want the player to be overwhelmed at first, and is scientifically accurate nonetheless.

And also I just now remembered: my reasoning for the “body plan” tab was to group together the organ system and other changes which would be less adding parts and more fundamentally changing the way your organism is structured. For an example with skin, having chitin has a very direct impact on the way your organism is otherwise functioning, as does the presence or lack of an organ, so I thought of organizing them into the same tab. But of course, it could be a bit disorienting if you jump from the internal structure and external structure of an organism in the same tab.

I said this before I remember, but given how fundamental the topic of embryology and germ layers have become to our understanding of evolution and phylogeny, I really struggle to see alternative forms of structure in complex organisms. These germ layers are hard-baked into the genomes of advanced multicellular organisms because true specialization needs a split into these groups of tissue. In fact, we define true cellular/tissue specialization as the presence of germ layers. Sponges, who don’t have germ layers, aren’t considered to have truly specialized cells, and fungi, who also don’t have germ layers, largely only have two types of cells (Fungal Cell - an overview | ScienceDirect Topics). Even plants have analogous structures for germ layers, with their structure being split into vascular, dermal, and ground tissue, and with plant phylogeny being heavily defined by the presence or lack of presence of each tissue.

Many organs are indeed oftentimes mixes of mesodermal and endodermal cells, but that is the nature of the mesoderm itself; because it is necessary to form muscles, any organ with muscles requires mesodermal tissue. The tissue composition of a specific organ oftentimes varies even when comparing the same organ across different species and clades, meaning the mesoderm is by-nature dynamic.

The introduction of this paper indicates some of this significance in the Introduction section: Germ layer-specific regulation of cell polarity and adhesion gives insight into the evolution of mesoderm | eLife
And this paper seems to suggest that there is a order behind the development of germ layers: Evolution of the Germ Layers.

I really like these concepts, well done. I personally feel like the concept art which explicitly uses the germ layers as sections provides an easier way to deal with progression, but the Internal/External concept art definitely has a lot more intuitiveness.

You are talking about internal organs. My tissue type idea so far is only for the external shape and structure. I have not thought about how to model internal organs really at all yet.
Other than that the system won’t be in initially, so I’ll do the next best thing for the brain and just have it be a metaball. I need this because getting to aware stage requires a brain so I need to put in some kind of placeholder in order to proceed to later prototypes.


I‘m glad you like the concept art, Deus:)

I have two comments regarding this:

  • Ideally, this kind of progression would arise out of the balance of energy intake and energy expenditure. If you don‘t have a gut, you‘re probably so bad at aquiring energy that having muscles wouldn‘t be viable anyways. Think of it like the aquisition of the nucleus: You have to guarantee your energy intake first before you can afford these cool new features.
  • If I understand correctly, some sponges have infact evolved something akin to a skeleton. I quote from the wikipedia article on sponges: „Many sponges have internal skeletons of spongin and/or spicules (skeletal-like fragments) of calcium carbonate or silicon dioxide.“
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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.