I was focusing on confirming details for the “muscle” part in the Multicellular Stage we are trying to implement, from the post linked below. Implementation details seem solid and I think are largely up to how much of this is worth it in regards to programming effort.
The larger question-mark however I think is related to how we will treat motility v. sessility as a player transitions to the Macroscopic. It’s a tricky question: we need to have some modicum of theory behind our decision, but the microscopic-macroscopic jump will be one of the most abstract and gamey parts of Thrive by necessity.
With how complex and large the jump between the microscopic and macroscopic world will be - and how the macroscopic will in many ways be a completely new game - I think we ought to make sure as many binding choices leading into the Macroscopic are as intuitive as possible.
Note that this doesn’t necessarily mean that the binding choices should be wishy-washy or have easily-ignorable effects: just that a player should clearly understand if they make X choice, that means Y in the Macroscopic Stage.
Starting off the discussion with two over-arching questions:
What traits in the Multicellular Stage will define a “motile” starting creature in the macroscopic stage? As in, the player will experience standard motile gameplay? The mere presence of muscular parts?
What traits in the Multicellular Stage will define a “sessile” starting creature in the macroscopic stage? As in, the player experiences gameplay with the future “sessile game mode”? A lack of motility parts? The presence of a specific “holdfast” part?
I actually have some decent hope, depending on what we can get implemented in Multicellular, that we can do a pretty intuitive transition. In theory every cell part and attribute from Multicellular can translate to a Macroscopic feature, even if the effects they have are different (in fact, I think that would be fun).
I am usually a big advocate for permanent choices, but in this case I think it would be logical if a species that starts the Macroscopic Stage as sessile can still unlock the ability to become motile later on. though for example unlocking muscle should be more expensive and difficult than in Multicellular.
Well, I think we should define the difference as “can you actively move in the Macroscopic stage?” with the question then becoming: What can make you move in the Macroscopic Stage?
I think we should do away with the “base cell movement” we see in Microbe and Multilcellular, that does not seem appropriate at the macroscopic scale, but other than that we have:
Muscle: I think any kind of “muscle” cell at the end of the Multicellular Stage means that your starting Macroscopic Stage species has enough muscle to wiggle itself forward.
Slimejets: We could have slimejets convert into a Macroscopic locomotion method? I know some bacteria do this, but it might not be appropriate for Macroscopic scale?
So, if your species has one of those at the end of the Multicellular Stage, then your starting Macroscopic Stage design has the features to be mobile. Perhaps you need a certain minimum propulsion to actually be motile? In that case you should be able to fix that with the tools available in the Macroscopic editor before actually entering the gameplay for the first time? (Because you have flagella/cilia tissue, you just need to place more of it)
I think we discussed previously whether actually using these in the Macroscopic Stage would require some nerve cell type. I think that’s still an option, but perhaps it will feel awkward to not start motile even though you have those parts?
I think if you try to progress to Macroscopic without above requirements, that should trigger a warning that you will start non-motile. (and you might be able to become motile later, but this will be more difficult)
As for sessile, I guess the biggest reason that we need to define these is for the LOD system that can populate the world with lots of static flora?
Initially, I would just say not motile = sessile. But those could technically also just be floating around in the water. So I guess it depends on whether the LOD system can handle things floating, and if we want it to.
I am guessing that the LOD system could handle things not anchored to the ground, but they would still be completely static in the gameworld, not reacting to currents. This would also mean that there isn’t much gameplay differentiation with species that actually are anchored to the seafloor.
So if we do not want to do that, we actually need a third category of “floating things”, with sessile species only being things that are actually anchored.
The obvious thing here is we do not actually have any holdfast mechanics in the Multicellular Stage, so they would have to evolve afterwards, or translate from something else in Multicellular. Lots of simple holdfasts use chemical adhesion, so maybe from slimejets/mucocysts?
So in my opinion we either have:
Sufficient max speed = Motile.
Not Motile = Sessile.
Or:
Sufficient max speed = Motile
Not motile and has a holdfast = Sessile
Not motile and no holdfast = Floating “sessile”
(speed that is too low “rounds down to 0”, becoming sessile)
I think if we add a system for sessile gameplay, it could handle non-anchored sessile life as well? It’s the same core problem: not much things to actively do, so you need some way to skip time.
In my opinion Motile/Sessile topic is the question of behavior. I don’t think we have to argue that sea anemones and clams are sessile, yet they’ve been known to show high speeds when moving.
If behavior settings will get more important in later stages, I think it would be a great way to introduce those. So maybe instead of using:
Sufficient max speed = Motile.
We could introduce:
Sufficient max speed * 100% motile behavior = Motile.
What I also feel could become a problem is where we should set Sufficient max speed bar.
I would actually argue that makes them not 100% sessile. Importantly, if the game needs to allow them to move that means they cannot be used by the flora terrain system.
As can be seen from the video, they very easily clear the criteria of “max movement speed above a certain small amount” even if we set it quite high. But indeed, by typical behaviour they are mostly sessile.
So they’re actually in a very similar situation to the sessile-not-anchored species:
Might spend a lot of time not actually doing much, thus needing a skip-time mechanic.
Is too dynamic to be used by the flora terrain system.
Maybe instead of a specific “sessile game mode” we just need a universally available skip time ability? That would fix these grey areas. And “fully” motile species would still use it for things like sleeping times.
This would obviate the need for separating species categories very harshly, other than flora versus non-flora.
This is difficult because behaviour is ultimately how the species usually acts, not what they’re capable of, and in particular what they can do under control of the player.
So what is the point of the sessile definition in that case? Part of my point in my first response was to figure out what exactly we want to actually define, and why.
I would set this very low. The only reason I included a threshold is because, as a community member pointed out in the past, you have cases like sponges moving a few mm a day. And I don’t want to for example exclude them from flora terrain generation because of something that isn’t relevant or even visible to the player.
I‘d like to point to an argument I‘ve made in another thread two years ago in light of this discussion:
The consensus back then was to have the smallest 3D organism be 1cm instead of 1mm, which I very much understand in retrospect. But that decision has ramifications for this discussion, namely: How is the smallest possible 3D organisms (ie the macroscopic starting blobs) motility hindered by the amount of oxygen it can get with diffusion alone?
The answer I have in mind is illustrated by flatworms. They can be up to 9cm long, but their body is extremely thin, 1-2mm at most, because they don‘t have a circulatory system and rely on diffusion for gas exchange.
This presumably represents the maximum thickness viable for motile organisms which rely on diffusion. For this reason I suggest that the player starts the macroscopic stage with an organism that is 1cm long, but qiet flat (~1mm).
This works quiet well with how the macroscopic stage currently starts, as it simply scales up each cell to represent a metaball. I suggest keeping the transition like this and making this flat starting organism able to move without muscles, relying solely on organelles line flagella and cilia for locomotion (which aren‘t be visible at this stage). But this flat mobile organism would need to develop a respiratory system and muscles in order to develop a thicker body (which could provide space for more complex organ systems) and still be able to move that thicker and heavier body.
I‘m not sure what comes first in this cascade of developments. Do muscles evolve which then necessitate dedicated respiration? Or does respiration evolve which then im turn allows gas-exchange-heavy muscles to evolve? Either way it feels like these are somehow tied together and are necessities for mobile organisms whose thickness crosses the threshold beyond which diffusion alone is no longer viable.
I think you are mostly correct, but I think beyond just not having what can be strictly described as circulatory system they don’t have a body cavity at all. By which I mean a fluid-filled space inside the body that is not made of cells/fluid, that oxygen and other things can diffuse through, even without explicit “pumping”.
(And what in my opinion also makes a difference is that this means a significant amount of the volume of the animal is not living cells, so not consuming resources. Jellyfish, sponges, etc. can get big, but have two layers of cells usually only a single-cell thick, sandwiching non-cell jelly.)
This is also a reason why if possible I would to have non-cell parts or cavities in Multicellular, so we can represent this at the scale where you’re thinking about cells. But whether you leave Multicellular without a cavity, or the Stage does not have that feature at all, I do agree that you should have to develop one in order to grow much in size (without being increasingly flat) in Macroscopic.
Mostly agree except for if we include the ability to create cavities in Multicellular. Species that have those could start out a bit more thickened.
We could also of course assume you develop a body cavity in the transition to Macroscopic, but I think that’s a missed opportunity.
I don’t think muscles and respiration are quite this linked, and muscles quite clearly pre-date specific respiration structures. Various tiny microscopic animals have muscle cells, and simple animals like jellyfish have them. This is also why they are on the Multicellular Stage roadmap. The flatworms you mentioned before also have muscles.
Respiration is in my opinion moreso linked with increased thickness and increasing scale in general, compounded by increasing resource consumption, like muscles of increasing size.
Like I think I mentioned earlier in the thread, Indo agree that cilia and flagella should have value here, but I think muscles should be the winner in most cases.
As for being invisible: the cilia on Ctenophores can be up to 2mm long, so I feel like they can at the least affect the visible texture?
You hit the nail on the head, I‘m mixing up a few things here… Yes, you‘re right that a body cavity would also alleviate the cellular gas and compound exchange/surface to volume issue like flatness would. And motility is an issue which is not congruent with that issue but still somehow interrelated. I guess the other problem might better be discussed in another thread (maybe in handling scale?)
Also, fair point about some cilia being so large that they‘d be visible on the starting scale of the macroscopic stage (presumably 1cm).
