Pilus, Defenses Against pilus, and pilus variations


A continuation of Melee Organelles with more emphasis on melee attacking and melee defense, we aren’t even sure if we only want pilus to be weapons.

It is also a continuation of a recent discussion we had on the slack general section.

Some of the things that have come up so far are:
Cell Walls, why cell walls should provide defense but not bar movement completely.
Predatory Pilus (for attacking and injecting agents)
And Membrane Pilus (for sticking to other structures)
And Sex Pili

Relevant Articles:



I have a short little idea pertaining to the thought that Cell Walls shouldent completely remove movement. My idea was that cell walls (since they no longer completely remove movement) should have a little equation for the speed they can output due to the thickness of the walls.

My little idea is that S = Base Speed (form flagella, Cillia, etc), C = Cell Wall Thickness, V = Density of the area (if we’re assuming different densities) and F for the final speed. The idea is that S / C - V • 2 = F. So say you have a base speed of 100, and say there’s a cell wall thickness of 4, then you’d have 25 Speed at first, then if we say that the water’s density is 1.05 (maybe chemicals or deeper depth) then the equation is 100 / 4 - 1.05 • 2 = 22.9 Speed… Is that a good idea or


I added a few more articles to the “relevant articles” list.

I am all for membrane pili, , I’m not sure what it could be used for in the microbe stage game-play wise, maybe sticking it down to stop a cell from moving instantly is an option.

Also, I agree, that it should make it harder to move, and yeah, that seems like a solid start for an equation, though the inside of cells is mostly the same density (cytoplasm) , the wall thickness should effect that in a major way.


IMO gameplay needs to take precedence over realism here. We want things as realistic as we can get them but we need to get solid, fun, combat which draws people into playing. The microbe stage will have a huge amount of combat in it so it really is going to rely on these mechanics and so they need to be satisfying and engaging.

There are several possible structures which could be included;

  1. A pilus which is a pure damage organelle, just like a spike or little sword (which is either static or can be retracted and extended).

  2. A pilus which can inject toxins into an enemy cell (again either as a static spike or a needle which can be extended on command) This overlaps with discussions about how agents work, which is the direction the rpevious thread ended up going.

  3. A pilus which is a structure for grappling with other microbes (which could be a really interesting thing but might overlap with engulfment) like this.

  4. A sex pili which can transfer genetic material (possibly gaining you some more mutation points?)

  5. Fimbriae which allow you to stick to a surface, though this overlaps with how movement will work.

IMO the best thing to do is to get on with testing and iterating. Just throwing something in and seeing what it’s like would be really cool.


I feel like the “Predatory” Pilus, or the stabbing one, should be able to extend while swimming. Maybe a little jousting gameplay for fast cells, which allows them to use their speed to rip through other cells?

I also imagine that a sex pilus would allow you a better long term bonus in mutation? As in say, you start with a +10 bonus in mutation, and then over time it can develop to a +50 bonus?.

Also, isnt Fimbriae just lampodeia? They sound like theyd have the same mechanics


I have another possible pilus variation:

It was on Cosmos, so I can only assume those microscopic blowdarts are scientifically sound. I looked it up (not on Wikipedia this time) and it seems like those darts would be trichocysts. Not sure if we want to represent those in the game somehow; I can’t really tell the difference between trichocysts and a pilus.

According to google, trichocysts appear and retract from the membrane in bulk. As in they can be shot out from all sides of the cell at once. Functions include: pushing back other microbes, anchoring, and injecting toxic whatevers. So if we wanted to add them, it would be a weaker pilus, but more of a small AoE type thing.


I have one final, slightly less realistic but still sound I think, pilus variety. The straw.

A lot of you may remember the Proboscis part in Spore’s cell stage? This is like that. It’s a quicker, more direct alternative to engulfment. You stab a cell and you start sucking out its precious compounds.

There is actually a predatory bacteria that does this (though not with a pilus) known as Vampirovibrio chlorellavorus. Essentially it targets green algae and attaches to the cell wall. It then transfers the contents of the algae to itself, leaving behind a hollow cell wall and membrane.

Info here: https://en.m.wikipedia.org/wiki/Vampirovibrio_chlorellavorus (yes it’s wikipedia)

In game I would imagine that as compounds are being siphoned from the prey cell, vacuole would begin forming in the predator cell and distribute the compounds throughout the cell.


I feel as if this (along with other types of Pilli) can make the game better in the way that I can make combat better than just going to a creature, being larger than it, and pressing E.One thing it would allow is that it can have a simple little countering system (such as Cell Wall > Pilli > Engulfing (> Cell Wall?)) and it could ensure little cellular arms races assuming there’s predation in cells. Also this would allow for targeting of specific areas such as say vacuoles if you can get your Pilli on them. Bassicly making the game a bit more complex.


I have always been a fan of the rock-paper scissors model for video game combat. Age of empires and other games do it very well, though I think we need more discussion about the particular model we want to use, im thinking all weaponized variations of the pilus would fit under the “Pili” section of that, but maybe shooting the trichocysts like mentioned earlier could be a counter to agents aswell so a cell could go for “physical” versus “chemical” ranged combat.


I made a silly diagram of the discussed pilus types. I condensed 3 and 5 into the grapple pilus because they are functionally the same


I like this, but I feel like AoE Pilus and Grapple pilus could be one in the same. And as you mentioned before, the blow dart variation is possible and would be a fun mechanic


The grapple pilus was a bit inspired by Type IV pili and Fimbriae, which are used in locomotion and adhering to surfaces. But yes I suppose they could be condensed.

The AoE pilus was supposed to simply push away surrounding cells whilst doing minor damage to them. Perfect for those situations where you’re crowded on all sides and a Gluttony cell is closing in fast. You know what I’m talking about


Just a quick question. Type IV pili and others that are used to puncture the membrane and inject toxins all evolved from a striped down flagella, are we planning on having pili be a flagella upgrade?


Type IV pili are actually used for locomotion.

I was thinking pili would be rigid flagella, but they’re made of different proteins entirely. It also might be complicating things to get a weapon from a movement part.


Personally I’d like to see stationary cells using pilli so I think they should be separate.


Well that’s the thing they’d become sedentary over time, as their flagella stiffen. But I agree with you nonetheless.

So does that mean we are including Type IV pili? I’m a bit confused on what the official decision is, or if there even is one?


No official decision. Personally, I think they’re all nice, and we’ll just have to start implementing some to see what works and what doesn’t.


I’ll likely implement organelles upgrades while doing agents for 0.4.0 since the two are really interwoven. That should give use quite a bit of specialization and diversity for pili.


I was watching a bit of coding train, which I highly recommend (choo choo)! He was talking about forward and inverse kinematics and I thought I would have a go.

This version could really be for any type of pilus, it’s just a bendy structure which can follow a point. It can also retract and shoot out again. The advantages are that it’s a very small amount of code and very light computationally so might work. Code in the prototypes repo as usual. Looks nice an organic I think.


Could we do that for the cell membrane? Seems like it’d be good for pseudopods :0