Membranes characteristics

Thanks for the feedback,

Regarding the questions:
@Narotiza, In the real world most organisms can survive in a relatively wide range of temperature. The more adapted to extremes however, the narrower the range your membrane will be effective. A middle-range membrane would be you jack-of-all-trades, not better than a specialized membrane in a specific environment and nowhere near able to survive extremes but able to exist in a wider range of temperatures and sharper variations like in tidepools.

Regarding the slider, i agree that this is a very good system and could definitely be used to change the membrane fluidity. Keeping it in the middle would make you great at resisting temperature variations and live in a normal range of temperature but anything a bit more extreme requires you to adapt by changing fluidity.

About the mix and match of membranes and walls, in real life you cannot mix and match any and all and there are metabolic/didn’t-stick-in-evolution reasons, but from a game stand point why the hell not? After all if the player is willing to deal with the consequences of having both a specialty membrane and a wall, this can make for some interesting options. The only limit I see, and that is from a balance/simplicity standpoint, would be to allow only one wall type at a time while any membrane could be combined with it. But again, that is only my way of seeing it and i do not know how hard or easy it is to put in game.

Finally for the Silica shell, I did say it does not block light and I understand that it can be a little misleading. Actually any wall or thicker membrane would block some amount of light. This is not much however, plants do most of the photosynthesis and have cellulose walls. At this scale I am not sure if this actually matters all that much but from a gameplay standpoint it could indeed be a good factor to have walls block some amount of light for photosynthesizing organisms. This amount should be small however as most of the photosynthesizing organisms in real life actually have a cellulose wall or silica/calcium carbonate shell.

@tjwhale, For the rate of sinking, i like the way you brought it up and can tell you some organisms do have vacuoles to increase their buoyancy. Most of the organisms living in the middle or higher part of the ocean rely on currents to keep them in suspension since things do not behave all the same at this scale. Indeed many diatoms, pretty much all those you can see that are oblong oval-shaped or banana-shaped are actually bottom dwellers in shallower waters where they photosynthesize and glue themselves to sand. This glue also holds sand particles together and diatoms are good at control erosion at a micro-scale.

About rigidity, it does not control temperature per say, but rather allows a cell to continue it’s normal life in different temperatures. Like i said earlier to Narotiza, average membranes are the jack-of-all-trade of ambient temperature while more rigid will allow to keep a normal fluidity in hotter environment instead of bursting. Fluidity increases with temperature and resistance is affected by membrane composition. A very rigid membrane will be as fluid in near a black smoker as a very fluid membrane will be in arctic conditions, each being adapted to match its living conditions. However the more specialized you are the least adaptable to change you become.

I must admit that as of right now I am a bit puzzled as to how to differentiate chitin from cellulose. At this scale pretty much everything is transparent to a certain degree but, yes, chitin more-so than cellulose. There are three main differences i can think of from the top of my head but i will look into it today: Chitin is a nitrogen rich-er material than cellulose. Cellulose walled cells tend to be more organised and geometric than chitin-walled cells, plant vs fungi. And last but not least in later stages on the game, cellulose could be reinforced with lignin to allow for woody plants instead of small herbs and ferns.

Hope that helps, do not hesitate to ask further questions!
In the meantime i have an appointment with some reference books to find more information.


I remembered a relatively important thing i forgot before. Cellulose is actually glucose chains that are bound differently from reserve glucose and chitin is nitrogen-enriched glucose that is also not bound like reserve glucose. Figured this could mean additional amonia and glucose to multiply / kind of a small upkeep of both for chitin. Also, an additional glucose cost to reproduce or upkeep for cellulose-walled cells, which, in real life, must allocate carbon to reserves, reproduction and cell wall and maintain some form of balance depending on conditions.


Here’s this silly thing:

I wanted to avoid completely different wall types being direct, linear upgrades of each other, so I made a mockup of a system where, when dragging the rigidity slider, you can pay a certain (relatively large) MP cost to jump a dotted line and unlock a certain wall type. It makes them all unique and unrelated, but I’m worried it also complicates things too much?

@Narotiza I love your doodles of these cells, they look very fun:) But I think your worries are very much warranted…
My counter-proposition: We leave the slider linear. On one extreme there‘s a fluid membrane, on the other extreme there‘s a cellulose/chitin cell wall. We don‘t really know what the gameplay distinction between cellulose and chitin would be anyways, so I propose we just make them the same thing and call it „cell wall“.
As @Estredar layed out in his long post, sicilia and calcium carbonate layers aren‘t really membranes, but shells outside of the membrane. So I propose we just put them into the „external structures“ in the organelle section and make them completely seperate from the membrane rigidity slider.
Something Estredar said which also supports this proposition is that the sicila-shell-bearers have a very fluid, amoeba-like membrane underneath the shell.

Interesting ideas. I agree that having a single slider doesn’t work so well with shells. If we put shells in the external organelles section then they are binary, there is only one thickness rather than a slider.

I’m open to options on this.

One possibility is to have a 2D selector, with the rigidity on the x axis (from soft -> normal -> double -> cell wall (both chitin and cellulose together)) and then have shells on the y axis (silica at the top -> none -> calcium carbonate at the bottom). That way you can have any kind of membrane and then put any thickness of shell around it. Cell wall + thick shell would be the ultimate defensive strategy.

@tjwhale I like the direction you‘re going in. But rather than have a 2D selection we could, you know, have two sliders. That‘s basically the same as far as I understand, just not as confusing to the player.
A reservation I have with either of these options (2D selection and two sliders) is that a slider/dimension which goes from silicia shell to no shell to carbonate shell doesn‘t really have a strong intuitive logic to it. It isn‘t intuitive that no shell is in the middle of sicila shell and c-carbonate shell.
Also a slider/dimension for shells wouldn‘t be able to control where to possible holes and spikes would be located on that shell.

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I want chitin cell walls, if we have a slide my proposal is you just choose the “chitin” texture, or the “cellulose” texture so you have some options.

Also, chitin allows for budding, which could be an alternative means of reproduction, so that could be the difference.


THANKS @Untrustedlife, That was the one detail i was trying to remember, budding, yeasts! Yes, chitin wall has the advantage of allowing budding. Budding could be exactly the same thing as mitosis in game with simply a different animation.

Once the rigidity slider enters “wall” territory, allowing the player to choose between different, purely cosmetic textures, based on the different wall types estredar mentioned, is a pretty simple way of doing things, however it doesn’t really show the player how different walls behave if they’re just reskins of the same general wall. It could work if we don’t want to implement different properties yet though, and it could be a nice way for players to customize their cell.

I do want to see different wall types in the game, I’m looking forward to trying to texture the silica shell especially.
(also I still think the chitin texture looks too dark)

I‘ve come up with a suggestion of how the different cell wall types could be implemented using the linear membrane rigidity slider:
Once you‘ve evolved a certain amount of rigidity (say halfway between medium rigidity and maximum rigidity) you have to choose which cell wall type you want. (cellulose, chitin, sicilia or calcium carbonate) This choice alters how your membrane characteristics will change as you further increase your rigidity. The only way to go from one cell wall type to the other after this point is to go back towards less rigidity until you have no cell wall again. After that you could evolve another type of cell wall if you want to.
If this explanation is confusing, this visualisation should help:

Excuse my writing, please.

I still think it would be even cooler if the sicilia and carbonate shells would be placed as hexes as it would allow for more variety. This is just the alternative I suggest if that turns out to be too complicated to implement.


Now that cell walls are implemented i think it’s time to discuss how would they regenerate when damaged. I thought walls could act as “shields” for the player’s health, like a secondary health bar, and once the wall is damaged enough the cell becomes more vulnerable.
Now, to regenerate walls the cell would need to gather materials like it does for reproduction. For organic walls like Celulose and Chitin that wouldn’t be a problem, both are made of glucose (chitin is a modified version of it) so any surplus would be used to repair walls. For mineral walls it would be more complicated, because we would have to add new compounds in the environment and that would mean adding new clouds with different colors. I’m down for adding new compounds, but it might get to a point were it becomes confusing.

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Personally, I think cell walls simply having a higher amount of health and damage resistance instead of being a second health bar is fine as it’s simple to understand and doesnt require more coding hours to implement. As for requiring resources to regenerate? That makes sense and It might be cool to have an additional strategic element to membranes than just selecting one that has better stats. For instance requiring glucose to heal with a chitin/celuose wall instead of ATP (That’s what you currently use to heal right?). This could make it a little more risky to play as a cell with walls if your not optimized for producing glucose yourself.

As for new compounds? If we really must add some for this I think the best way to go about it would be to implement it as an enviromental factor rather than an in-game resource. Like how oxygen works. So your diatom fellow would heal faster in silica-rich biomes. However; I dont think it’s neccessary to add new compounds to the game unless they have more than just one use.

Healing has currently been balanced to happen as long as you have more than 0 ATP, but it doesn’t consume any ATP. So healing is basically free as long as you aren’t dying from running out of ATP.

I agree, we shouldn’t add a new compound just to heal.
So basically the cell wall would end up just being a buff to health amount and/or damage resistance. Perhaps it could also affect the health regen rate of cells.

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For mineral walls, would it maybe make sense to add new materials that float around (like iron does atm) but instead of giving you a compound they just regenerate the well depending on how much you consume through engulfing? I dont know if its realistic at all though

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I personally think it would just be best if we stuck with a simple method of healing using ATP or glucose for now. As I said before, I would prefer that compounds and such things have more than just one use, as that would basically be a soft implementation of a silica compound. We would also need to communicate to the player that if they have one specific type of cell wall, they would need to seek out one specific type of rock to heal.

I would certainly enjoy more scenery in the microbe stage though.

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Lately, I had been fixated on finding a way to properly simulate differentiation between herbivores and carnivores in Thrive. The trouble being that nothing would stop carnivores from eating plants, or herbivores from eating animals.

Originally I had focused on the implementation of two types of storage compounds, glycogen and starch, to differentiate plant from animal and define these diets. However; After a pleasant discussion with Untrustedlife who had presented the idea of a cell wall-based diet, we decided that creatures will need to adapt to consume different wall types.

Bear in mind that this is a rough concept right now.

Main Idea:
In order to provide a more refined distinction in heterotrophic diets, engulfment will be reworked to require different enzyme types that contribute to a total “efficacy” rating. The more efficient a cell is at consuming a wall-type, the more resources it will obtain from it’s prey. (For example, a cell with 40% lipase efficacy would receive 40% of it’s compounds upon successful engulfment. Should the cell have 0% efficacy for the required enzyme it will be unable to damage the target cell via engulfment.

As a result; All cell walls will become completely invulnerable to engulfment from predators, until they adapt the proper enzymes to bypass this resistance.

Engulfment Resistance:
Different cell wall types will now be resistant to engulfment from predators lacking the prerequisite enzymes.

Single and double membranes will remain vulnerable. All cells will have an initial 20% lipase efficacy, allowing them to consume these types of membranes at all times.

Cellulose and Chitin can only be engulfed by cells possessing cellulase and chitinase respectively.

Calcium carbonate and silica wall resistance will be effected by lipase until more information on predation of coccolithophores and diatoms is provided. Their high health will still render them resistant.

Lysosomes and Enzymes:
In order to prey on walled cells, organisms will need to obtain a lysosome, the initial lysosome part is a single-hex vesicle containing lipase. From there, it can be upgraded to instead provide the host cell with different enzymes such as chitinase or cellulase. Each lysosome can only utilize one enzyme at a time.

Lipase: The initial enzyme, cells in Thrive will always have a minimum 20% lipase efficacy. lysosomes containing lipase will further increase this efficacy by 20%.

Cellulase: Lysosomes can be upgraded to provide 20% efficacy for cellulase, enabling the cell to engulf and digest cellulose walls.

Chitinase: Lysosomes can be upgraded to provide 20% efficacy for chitinase, enabling the cell to engulf and digest chitin walls.

The hope is that in addition to differentiating heterotrophic diets, this feature will also provide cell walls with additional benefits by further decreasing the amount of potential predators.

As always, feedback is appreciated, and please let me know if anything is particularly incoherent.

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I took the initiative to add in digestive enzymes mechanic for the engulfment revamp (not the whole enzymes system) and now have the basic functionality working: select lysosome → modify → select enzyme (lipase, chitinase, cellulase) → chitinase and cellulase unlocks walled cells consumption. Try it out from this commit.

Since calcium carbonate and silica membrane have no counter enzymes, I’m not sure whether these two should be digestible or not with the way how digestion in the engulfment revamp works. It’s either in or out (health is not taken into account) and if they are still affected by lipase they’ll have no advantage over predator’s engulfment.

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In reality, calcium carbonate and silica bear no advantage against engulfment, but are very resilient to physical harm. Some smaller organisms have adapted specifically to be able to crush up the frustules of these walls.

In Thrive, species using these walls will probably need to take advantage of the reduced osmoregulation costs to increase their relative size as a counter to engulfment. It’s that, or we need to come up with some special handling to make them less susceptible to engulfment now that it is more effective.

Ah okay, didn’t know they aren’t actually really immune from engulfment irl. Then they are the perfect candidate for the pili resistant membranes I mentioned a while ago, engulfment should be their weakness still.

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I was thinking about the transition from placing cells to placing tissues when a question came to my mind:
In my understanding silicia and calcium carbonate walls/shells are different from cellulose and chitin membranes in that they aren‘t really part of the membrane, but rather a second, anorganic shell that is produced around the membrane.
Are there known cells with silicia or calcium carbonate walls that form colonies and/or multicellular organisms?
I find it hard to imagine that cells with such an anorganic shell can form coherent and sufficiently merged tissue. I‘m just a graphics guy but maybe someone more knowledgeable can tell me if and why such cells can or can‘t form colonies and/or multicellular organisms.