Membranes characteristics


Hi, with this post i would like to know your opinions about membranes, how they works, why player should choose one instead another, how to create them.

I image membranes as a structure, so they could be in the editor as another sub-section of structure section.
I think that as organelles membrane should cost mutation points, corresponding on their characteristics and give different powers.

So here my stats about membranes:

Single membrane: default membrane cannot be added
perform: engulfing, eating compounds.

Double membrane: can be added in editor.
cost: 50 mutation points.
perform: increase hp of x value.
give a chance (in percentage) to avoid toxins damage.
consume more ATP than single membrane.
decrease speed.
requirements: single membrane.

Wall membrane: can be added in editor.
cost: 90 mutation points.
perform: increase of hp of x value (higher than double membrane).
give a chance (in percentage higher than double one) to avoid toxins damage.
consume double ATP than single membrane.
considerable decrease speed.
requirements: single membrane.

Chitin membrane: i don’t really have any idea maybe increase store capacity and speed of eating compounds.

In my idea double and wall membrane are to different kind of gameplay, with wall membrane you probably play aggressive, always try to kill other cells and take their compounds, with double membrane you play both aggressive and also quite eating compounds, could be best balance but most aggressive cells can still kill you.

Staying in single membrane will give you advantage in speed, on the other hand fast microbe with toxins, or big cells can easily kill and eat you.

In appearance section player should have option to change membrane color, maybe also choose which one instead of get back in structure and select it?


I feel like membrane type should go in the appearance section.


I like the ideas though.


My Idea:
Single membrane: default membrane
To switch back to it from another membrane it costs 90 mutation points.
perform: engulfing, eating compounds.

Double membrane: can be added in editor. (Via appearance section)
cost: 90 mutation points.
increase hp by 33%
50% chance to avoid toxins
consume double ATP than single membrane.
decrease speed.
requirements: single membrane.

Cell Wall: can be added in editor.
cost: 90 mutation points.
perform: increase of hp by 50%
Perform: pilus defense percentage of some kind
consume same ATP as single membrane.
decrease speed 50%
requirements: single membrane.

Chitin Cell Wall: can be added in editor.
cost: 90 mutation points.
perform: increase of hp by 33%
consume same ATP as single membrane.
decrease speed 33%
requirements: single membrane.


I like it. I actually had a somewhat similar suggesetion a while back. I proposed that a cell could have several types of membranes with different properties (for instance “chitin wall” at the back and “acidic membrane” at the front. In this example the acidic membrane would be the only surface area capabale of engulfing, while the chitin wall would be unbreakable if engulfed (You would need pilus or toxins to shatter it) and incapable of holding surface organelles (flaggelas and such).


Sounds like a lot of nice ideas.

One thing I wondered about is a spectrum / slider rather than a binary choice. So you can choose a value for the cell wall from 0 to 100, where 0 is super thin and fragile but very light and 100 is super thick, robust and heavy. Maybe moving values would cost 1MP per amount moved (so going from 0 to 100 would cost 100MP but you could do a little 5pt adjustment for 5MP).

The hp of the cell wall and the amount it slows you down could then also scale, this allows the player to tune the cell how they want. Reducing damage and giving more hp are generally the same effect. For example 100hp and 50% damage is the same as 200hp and 100% damage.

Would a tougher wall use more ATP? I’m not and expert, isn’t the value of a thicker wall that you can do less osmoregulation and that saves you energy?

In terms of having different areas of the cell do different stuff I am concerned it would be hard to see. I play reasonably zoomed out and it’s already relatively hard to see what organelles a cell has, let alone if the cell wall is broken up. However I do think there is a lot of good potential gameplay in having a tough zone and a weak zone, that could be pretty fun.


I agree with @tjwhale that the membrane should be controlled via a slider. You start in the middle, with a normal membrane. In one direction there‘s rigidity, so a cell wall, and in the other direction there‘s fluidity, so a thin cell wall. Cells with a very fluid membrane would basically be amoeba-like. That means faster, because the membrane‘s lighter, good at engulfing, because a „fluid“ membrane can wrap around prey more easily. Obviously the thinner the membrane, the more fragile it is.
I think the mutation point costs all of you propose are way too low though. Do we really want a species to go from the most fragile membrane possible to the sturdiest cell wall there is?
I propose to increase the costs the further you stride from the starting point. If you want to make your membrane thicker the first time it might cost 10MP, the next time 20MP, then 30, 40 and so on. This way we have some gradual progress through the generations.


I like the idea too of slider, appearance should be an area in which each player can express his own creative.
But i think there are some problems.

1 - Now membrane are like 4 static type, also in models, if we use slider parameter we should change the model with this parameter?

2 - Membrane should have some parameters, like for organelles, how we can decide to set that parameters if is not static choice? Maybe we could use this slider thickness number and use it as main operand that change other parameters like mass, capacity of engulf ecc…

Finally i do not think that change membrane should cost every time more, it’s my opinion but giving freedom i think could create more opportunity for creation, dynamic situation in which player use brain to adapt his own cell to new challenge, if do it cost every time more, or we reduce challenging or we not prevent player to change as many time he want membrane.


One way of dealing with having 4 models is to lay them out in a line. So if your membrane value is 0 -100 then it could be 0-25 = thin membrane, 25 - 50 = normal, 50 - 75 = double membrane and 75 - 100 could be a thick wall. The effects could be continuous (hp = membrane value, for example) but the models suddenly change at these values.

I’m not totally sure what chitin is and how it makes things different, does is make tough walls?

There could be multiple sliders or multiple different things you can choose however I quite like what you are saying @Dak28 of just having one thing to choose and everything else derived from that.

Also we can do several passes on this if we want. So maybe first time round we just introduce one thing you can change and then in a future patch we could add more options if people think the system is really cool.


I‘m not sure if this kind of reposting is appreciated, but I just found some great concept art of this in another thread (Prokaryote Gameplay)

I thought it might be helpful to put this here. What‘s the point of good concept art if it‘s not visible where people discuss the exact things that concept art explains?
Sadly I don‘t know who created this.

I think this general idea, coupled with a slider, provides the best option. It‘s still a two way slider, but the balancing is more interesting than a simple defence vs speed slider. This way it‘s more defence vs speed vs engulfing.

As you can see in the table above, this could be quiet balanced if we do it correctly.


I‘ve done a finished concept of how the membrane section of the editor would look.

The only slider which the player can control directly is „rigidity“, the other characteristics would change depending on rigidity.
The GUI design is based on @Narotiza‘s Circular health/ATP/reproduction progress bars. During an editor session the player can access the patch map and a report of what happened during the editor session represents.


I like a lot the sliders and how they looks, i have just a question,
what did you image is flagella efficiency?

I imaged a slider of speed that can be increased by adding flagella, reducing by adding other organelles or improve rigidity.


I think cell walls are either very heavy or completely unable to support external organelles like flagella and cilia, and low-rigidity cells are too fluid and flagella would just end up pushing one part while the rest stays behind:

Meaning medium-rigidity cells have the highest flagella efficiency.


But efficiency doesn’t affect speed directly?


@Dak28 Alright, in that case efficiency isn‘t the right word. I meant exactly what @Narotiza was talking about. Is effectiveness the right word?
The idea is that it would be about 100% for microbes with cell walls or normal membranes, but rapidly decrease as cells get more amoeba-like. For microbes with cell walls weight would drastically increase, making autolocomotion increasingly infeasable. But these need to be two seperate stats weight also influences how well a cell can be pushed around, while flagella effectiveness doesn‘t do that.


Hi, bellow you will find a general description of cell membranes and walls. I tried to limit the details to things useful for the game development and put forward some game-related characteristics and ideas. If I went too deep or neglected some details do not hesitate to ask questions and I will be happy to answer.

  1. Membrane(s)

1.1 Membrane fluidity

Membranes may appear as a solid barrier isolating the organelles from the outside world but this limit is actually quite flexible and can almost be considered a fluid. This fluidity is necessary for the cell as it allows the membrane to flex and create vacuoles for phagocytosis. The fluidity of a membrane is strongly influenced by its composition and is usually adapted to the cell’s environment.

Temperature is the main factor when it comes to cell membrane fluidity or stiffness. As a rule of thumb the higher the temperature, the more fluid a membrane becomes, up to the point where it breaks from thermal stress. The opposite is also true and a membrane becomes stiffer the colder it is, eventually impeding the cell’s ability to exchange nutrients and metabolic trashes with its environment. It can become so cold that ice crystals may form inside a cell and, much like a knife, breach the membrane.

In this regard micro and macro organism have a specially tailored membrane composition. Organisms with stiffer cell membranes are usually living in hotter conditions and those with a more fluid membrane tend to be living in colder climates. This, overall means that they have a comparable membrane fluidity but at wildly different temperatures.

The best examples would be extremophiles: thermophile bacteria were found to have “cheated” the usual composition and added special lipids to their membranes that stiffen it a lot, allowing it to tolerate the extreme temperatures found near black smokers. Its membrane would probably be solid at room temperature. On the other end of the spectrum there is an arctic fish that live in waters that can reach -4 degrees Celsius and, yet, does not freeze. It membranes are very fluid and would likely easily break if brought near a black smoker but given the low temperature, it is just fine. It even evolved a natural antifreeze agent that clumps with tiny ice crystals forming in its blood and cells and stops them from growing to a dangerous size.

1.2 Membranes

Some organisms have more than a single membrane. Bacteria have what could be called a triple-membrane as it is composed of an inner lipid bilayer, an intermediate layer of peptidoglycans and another external lipid bilayer. All these layers serve as additional protection and serve as an anchor point for some external structures like flagella.

I do not know much about organisms with multiple membranes however and this is pretty much it from the top of my mind.

  1. Cell walls

2.1 Without cell wall

Most organisms without a cell wall are either amoeba-like or have an internal cytoskeleton made from protein fibers to keep their shape. The greatest disadvantage of a “naked” membrane is osmoregulation as the entirety of the membrane is exposed to the environment. They are, however, those that can engulf the biggest preys and can achieve some motility using pseudopods.

2.2 Cellulose wall

Most common in plants, trees and algae cellulose walls are extremely resilient to internal pressure. If its osmoregulation fails and it would normally burst, the cellulose wall will keep the cell intact for quite some time (I once ran an experiment where we put some carrot cells in distilled water and it took it about 10 minutes before I saw some cells burst). It is also very resilient to physical damage and, to a certain extent, chemical damage. However the right enzyme can make short work of cellulose, take the fungi decomposing wood as an example.

2.3 Chitin wall

Found in fungi, chitin is kind of a middle ground. It does offer some mechanical resilience, it is kind of hard to break down without the right enzymes but is otherwise unremarkable as far as I know. It is very much not my area of expertise though and I am probably missing some details.

2.4 Silica shell

Not a true wall per say but could be considered like it in game mechanics. It allows for some of the sturdiest protection while not stopping light for photosynthesis. A large amount of organisms with a silica shell have spikes and other defensive structures. Ironically most of the organisms with a silica shell move like amoeba, using pseudopods protruding from tiny holes and openings in the shell. The main disadvantage of a silica shell is sheer weight and they have a hard time not sinking. Another disadvantage is the raw material needed to produce this shell and silica can sometimes be a limiting nutrient during blooms. Art note: though most micro-organisms aren’t incredibly cute or something, Diatoms, Silicoflagellates and radiolaria could be called artists and are quite pretty.

2.5 Calcium carbonate shell

There are two types of calcium carbonate shells, those made out of calcite and those made out of aragonite. I do not know if this is too much detail but I will go ahead anyway. Both are quite sturdy and also heavy but most organisms with such shells also have flagella that allows them not to sink or control said sinking. Calcite is most resilient to chemical stress and can stand lower pH than aragonite. Aragonite is, on the other hand, more resilient to physical stress than calcite and relatively sturdier overall. Both have a huge advantage and a corresponding disadvantage. The advantage is that calcium carbonate is extremely plentiful and is almost never a limiting factor to their growth. The disadvantage is that there is a limited depth at which calcium carbonate starts dissolving. At a depth between 4000 to 5000 meters, calcium carbonate dissolves completely and no organisms with a calcium carbonate shell can survive bellow said depth.

  1. Graph

Here is a little graph to summarize it all and a few of my ideas on how it could be implemented in the game.

Membrane/Wall Advantages Disadvantages Example Organisms
Simple Membrane None, standard None, standard Euglena, Amoeba
Double Membrane Chemical and physical resilience Maintenance costs, slower exchange with environment Most if not all bacteria
Without Wall Easy phagocytosis (larger engulf radii), mobility through pseudopods High osmoregulation cost, vulnerable to physical and chemical damage Amoeba, most animal cells, choanoflagellates
Cellulose Wall Low osmoregulation cost, highly resilient to chemical and physical damage Very weak to specific enzymes, low mobility, slower exchange with environment Plants, algae
Chitin Wall More resilient to most damage Lower mobility, slower exchange with environment Fungi, Yeasts
Silica Shell Most resilient to physical and chemical damage, lower cost of spiky defenses, very pretty Very heavy, increases sinking rate dramatically / lowest mobility, increases cost of mobility-related organelles Silicoflagellates, radiolarian, diatoms
Calcium Carbonate Shell Resilient to most physical damage and slightly resilient to chemical damage Heavy, slightly increased rate of sinking / low mobility, slower exchange with environment Dinoflagellates, Coccolitophores

Don’t hesitate to ask questions!


Thanks for all the details and the handy list, this will really help us out. And i agree on most of them. Though im not sure how we make the silica shell work, as “sinking” isnt something we have to worry about in-game right now. Maybe it makes you move slower instead?


In real life it is usually sinking bellow the photic zone that kills diatoms over being eaten but that’s just real life, it is not so fun isn’t it. It would indeed be easier to simply have silica being the “tank mode” and have it move the slowest of them all instead of including a whole mechanic for the rate of sinking.


This is really useful and interesting, thanks for posting this!
Some things I’m curious about:

You mentioned membrane fluidity having to be based around an environment’s temperature for a cell to survive there. Is there a way for an organism to achieve a wider range of temperatures it can survive in? What should the highest range be?

How do you think all this could work with the membrane rigidity slider concept posted above? Do you think a different system could work better? I get the feeling it’d be strange if you were to evolve a silica shell from one of a completely different material, and I believe both a one-dimensional slider and a list of options wouldn’t be very good in that regard.

Could the player mix and match the different membrane and wall types in the editor, or does it make not enough of a difference to matter like you mentioned in the discord?

In the entry for Silica Shells, you said it allowed for “some of the sturdiest protection while not stopping light for photosynthesis.” Are there stronger shells that do block out all the light? I think a wall like that could lead to some interesting gameplay.


This is really great info, thanks for taking the time to write it. I guess the factors that can relatively easily be changed gameplay wise, as you say, are: resistance to physical and chemical damage, movement speed, osmoregulation cost, ability to engulf, amount of damage taken when osmoregulation fails, cost of pilus, depth at which you can exist.

We could maybe change the rate at which you pick up compounds from clouds, or maybe the radius you pick things up from, though that might be frustrating.

In terms of sinking we could have a mechanic like “in order to exist in the mid or high ocean you must be neutrally buoyant or better” with vacuoles and cytoplasm giving buoyancy and having a shell taking it away. That might be interesting. It would also allow the most shelled creatures to exist in the tidepool as they could be as heavy as they want.

I really like that the membrane rigidity can be used to regulate temperature, we haven’t talked too much about temperature but rolling it in to membranes sounds cool.

One question I have is how we differentiate Cellulose Wall from Chitin Wall, they don’t seem to be particularly different. Is Chitin transparent? Maybe that could be a differentiating factor like the shells.

Also, you’re right, radiolarians look great :slight_smile: