Agents Discussion

To me this sounds way more like organelle upgrades. As the behaviour is the behaviour of the AI members of your species, and not how your toxins “behave”.

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Recently, I had an idea to increase the depth of the toxin system. Right now, it’s as surface level as it gets. My idea is to have toxins that can specifically target different functions of the cell, or just a generally bad toxin.

Each toxin can affect components of each cell, like disabling flagella, ATP production, of membrane integrity. When a toxin specifies a component to attack, it loses the effectiveness to attack other components, which enforces specialization. Then, each cell would also come with an antibody system. If a cell produces some toxin, it would also have to produce the antibodies for that toxin, which would require energy. The amount of energy each antibody requires is based on the disruptiveness of the toxin. So, a toxin which shuts down the flagella would not require much energy, but a toxin that destroys the cytoplasm would need a lot of energy to maintain.
This would cause more interesting prey/ predator relationships. A prey microbe might develop a toxin that disables the flagella of their predator, and allow them to get away easier. But the predator would probably develop cytoplasm toxin to damage their prey, without needing to be right next to them.

Here are the values I think would work well:
flagella toxin: 1 atp/s to make the toxin, 0.1 atp/s to make the antibodies.
Glycolysis toxin: 1.15 atp/s to make the toxin, 0.15 atp/s to make the antibodies.
ATP toxin: 1.3 atp/s to make the toxin, 0.2 atp/s to make the antibodies.
membrane toxin: 1.6 atp/s to make the toxin, 0.3 atp/s to make the antibodies.

In addition, a microbe who doesn’t make the toxin, can also create antibodies, but it requires the amount specified above.

What do you think? I remember seeing some stuff a while ago about adding better toxin mechanics, do you think this fits?

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I hope you don’t mind, I moved your post to the thread where various possible different agents have been discussed (the general term we use for toxins).

I don’t mind. By the way, do you know where the agent actually harms the microbe? I’ve spent about an hour and a half looking for it, but I just don’t know the codebase well enough yet. I’m trying to see if I can make a fledgling prototype of my idea, but can’t really do anything until I can change how the microbe is harmed.

Look in the AgentProjectile class. Specifically AgentProjectile.OnContactBegin calls Microbe.Damage.

I’ve been proceeding through the roadmap and have been attempting to generate discussions to finally nail down concepts which have yet to be fully concluded. Discussion has started for combat (Comprehensive Combat Revamp) and the upgrade system (Upgrades, Unlocks, & Endosymbiosis Master Thread) so up next is the Toxin/Agent discussion.

I’ll kick things off by listing pre-established ideas, providing some commentary, and noting where things are less established. I’ll propose a baseline idea to get the ball rolling.

Delivery Methods

Discussion of the methods of agent delivery have been pretty productive recently, and is probably the most finalized part of this concept. The combat thread provides more details, but generally, there are three ways of using toxins…

  • Spewing toxin clouds. This will be the only way prokaryotes will be able to use agents. In Discord, @Buckly mentioned the idea of not necessarily having this toxin be a “cloud” but more like an “aura effect”, where cells in a certain proximity to a toxin-spewing organism get a poisoned effect and take damage. I was skeptical at first, but I think this accurately reflects how bacteria use agents – not necessarily “predatorily” like shooting it at something to eat it, but rather, passively in an attempt to carve out more ecological space in accessing a nutrient. This paper (Bacterial competition: surviving and thriving in the microbial jungle - PMC) provides a very good overview. I like the aura idea, but we should make sure that, firstly, players aren’t constantly boxed in by a toxic prokaryote, and secondly, that players are able to see where exactly an aura begins and ends.
  • Utilizing it in a specialized combative organelle. There are various organelle concepts laid out in the combat thread listed at the beginning of the thread, but the basic idea is that certain eukaryotic organelles will utilize toxins to inflict direct damage on another cell. For example, the most well-developed of these organelles is the nematocyst, which essentially is a poisonous spike which rapidly thrusts forward and is discarded. This will represent the more predatory and direct method with which eukaryotes utilize agents.
  • Endotoxins. Essentially toxins which aren’t spewed, but are instead kept within a cell as a means to deter predation. These are defensive, and are able to be utilized by both eukaryotes and prokaryotes.

Agent Customization

I went down a huge rabbit hole of thought, trying to make a decently customizable “lock-and-key” method of toxicology and immunology. But I couldn’t settle on system that was easy to comprehend and without major flaws. These concepts included:

  • Having preset types of toxins which are more or less effective depending on the player’s morphology. So Toxin A would be more effective against cellulose aerobic organisms but less effective against chitinous iron-respiring cells, toxin B would be different, etc. But I figured that, firstly, this would mean the player wouldn’t have much of a capacity to build immunity if we made these buffs and debuffs mean anything (they’d always be weak to something), and secondly, most players will realistically go either with a purely aerobic organism or a photosynthetic organism as they transition to the multicellular stage.
  • Having toxins be either A, B, or C toxins and having immunology be focused on splitting three sliders in the nucleus between investment against A, B, or C toxins. Then there was the question of what stopped a player from just rapidly shifting between toxin A, B, or C to make sure nothing could adapt to them, or how much attention the player would give to immunology after figuring out an optimal blend of resistance.
  • Having X types of toxins and X amount of immune system patterns, with each immune system pattern having different resistances and weaknesses. It was too rigid in my opinion.

Ultimately, I began to ask myself: as cool as a constantly changing immunology landscape sounded, would it really be necessary considering the presence toxicology has in the gameplay loop? Ultimately, the only thing we need from a toxin system is an ensurance that…

  • The various toxin-parts we have conceptualized are viable, and
  • That cells have atleast some measure of shielding themselves against toxins.

We don’t need a constantly adapting network of locks and keys between toxins and immune systems in the cell stage; in-fact, it would probably be too much to pack in, considering the fact that players would also have to manage their environmental tolerance ranges, their upgrades, endosymbiosis, etc., and considering the fact that we would have to refactor this system for the macroscopic stage continuously. If the toxin and immunology system was the major focus of combat in the Microbe Stage, then such a system would be warranted; again however, toxins are simply an avenue of the combat system in Thrive, used by, at the most, 4 parts.

I think we’d want a slightly more complicated toxin system for the macroscopic stage. First, there actually are more things we can play around with in regards to agent-warfare in the Aware stage (certain toxins target certain systems for example). And second, we understand toxicology in that regard better. We have more room to create an easily-comprehend system there I feel.

Baseline Proposal

You will be able to customize the effect of a toxin. Each delivery method will deliver a base amount of damage, but additional effect damage (and, well, effect) is customizable by the player. There are various effects available depending on the nature of the part:

  • Pure Damage: Increases damage. The default, so it isn’t a specified toggle; it’s just what is applied if another effect isn’t specified.
  • Damage-per-Second: Akin to the more traditional poison effect in most games. Lasts up to 10 seconds. (Isn’t an option for toxin clouds/auras because that part is inherently DPS).
  • Disable Movement Parts: Disables cilia and flagella. Without resistance, lasts up to 15 seconds.
  • Obscure Vision: Constricts how far you can see. For AI, this would stop threat detection and scramble movement. Lasts up to 20 seconds.

Of course, more ideas for effects are welcome. I would like to note now that toxins still apply damage if another effect is chosen, just not as much as the default “pure damage”.

There are two methods of immunology:

  • Modification of certain organelles: For example, the mitochondria will have an anti-toxicity slider which will slightly boost generalized resistance to all effects. This will take away from the energy-production capabilities of said parts, however. You can get up to a 2% generalized resistance, at a cost of 30% of the organelle’s total energy production (obviously we should rebalance if inadequate).
  • Peroxisomes: Peroxisomes are essentially small organelles containing enzymes which assist with metabolism. Also relevant to this concept, they can breakdown toxins. Peroxisomes can be placed down like lysosomes and will provide 5% resistance to a specific toxin effect for 3 ATP. You can select what toxin effect is targeted in the Modify tab.

Note that immunology nullifies the total damage (base+effect) and the actual effect itself. So, damage gets reduced, and, for example, vision gets obscured for 15 instead of 20 seconds.

I think it is important to ensure that a toxin can never fully be nullified. Even the most resilient animals we can think of, such as the mongoose and honey-badger, aren’t completely immune to venom, for example. And in cases where animals are able to completely ignore a toxin, such as in clownfish or in sea turtles, the resistance is more due to morphology rather than some innate immunity in the blood; leatherback sea turtles have tough skin and a digestive system finetuned to eating jellyfish, while clownfish secrete mucous which prevents their skin from coming in contact with sea anemone stingers.

Concluding Thoughts

There’s a minimally viable system I feel can serve as a good baseline for toxins in Thrive. It’s pretty easy to understand while still offering some customization options.

If there were concluding thoughts I would like you guys to think of after reading this proposal, it would be a few things.

First, there is room for a more elaborate toxin system in the future, since, again, there is a good amount of easily accessible information out there regarding the use of venom, poison, and other toxins in multicellular life. However, perhaps we would infact benefit from a lock-and-key method in the Microbe Stage. If you feel so, don’t hesitate in bringing it up.

Second, I’m starting to wonder if an idea like the enzyme concept menu from a bit ago is becoming more necessary. We have lysosomes and now potentially peroxisomes implemented; though they aren’t exactly enzymes, those are rather small and abstract organelles which might not cohesively be represented by the traditional part-placement for other components in the Microbe Stage. Honestly, I forsee us potentially using a similar solution for environmental tolerances in the future, which would mean three very small and abstract types of parts that can clutter the editor.

A whole other tab in the editor or something like that is unnecessary, but I wonder if we can put a Modify button on the nucleus which would essentially compartmentalize things down and provide the same effect. A nucleus Modify menu could essentially condense everything, showing the enzymes/microcomponents as a graphical list of sorts and providing options for the player to add or subtract to the number of each component present.

One thing is that prokaryotes obviously don’t have a nucleus. So perhaps the origin cytoplasm is treated as a plasmid until the nucleus is placed, which allows you to tweak your enzymes.

Otherwise, maybe it is time to more seriously consider a passive protein/enzyme system. A previous concern I had was related to how many proteins we could come up with and how far down the macroscopic stage we could make it a relevant system. Perhaps the protein system can have perks which are the closest thing to an outright flat upgrade in Thrive, and perhaps that can open the door for more customization and gameplay.


This is a good overview of our current concepts for everything agent related!

I must admit I have always been apprehensive of the lock and key concept. In any form of implementation it introduces a nice amount of depth that encourages players to adapt against new threats or specialize towards familiar ones, but at the cost of greater complexity and steeper learning curve for players to surmount. Thrive is already a pretty complex game, and any player with a shaky understanding of biology tends to have a lot of trouble figuring things out.

My biggest concern being that players might easily be stumped by their toxin resistance not working against species, not realizing their resistance is not effective to the toxins they encounter.
The biggest thing that would cause this is identification. How would players be able to recognize one toxin from another? Different colors?
Would cells have a clear indication of what form of toxin they possess? Normally players would be able to learn what is safe or not through trial and error, but when your reliable source of food is suddenly using a different toxin, you’re in for some unforeseeable trouble.

My only idea at the moment to remedy this, should we decide to implement this feature, is to lock additional toxin types behind a game setting as part of difficulty settings. That way, players would be able to play with just a single toxin type, and not worry about being overwhelmed by additional types until they are ready to take it on. Perhaps a part of hard mode?

The history behind the enzymes system is a messy one; It was hotly debated on what parts should remain as parts, or be transitioned into the passive slots concepts. On the extreme end, prokaryotes were proposed to not have any parts outside of external and cytoplasm. In a way, it represented a sort of crossroads for Thrive’s development, and a potential paradigm shift on how editor gameplay would play out.

In the end, we decided that keeping enzymes/proteins as placable parts was the better option, as that provides a more visual and interactive way for players to design their cell. Hh personally compares the building of your cell to that of a factory such as in games like Factorio, which is the sort of constructive sensation we decided to preserve.

Personally I think the enzymes system as it was originally envisioned should be laid to rest. If we do indeed have need for something like it, I would consider a revisioning of the membrane tab as a home for all adaptations cell-wide.

Cell-wide features such as protein temperature tolerance, internal osmotic concentration (salinity control), toxin characteristics, etc, could be fine tuned from this tab in a similar way to selecting a membrane or using a slider. This would eliminate the need for a new tab, while still keeping things sensibly ordered. These wouldn’t be enzymes or proteins, because they are traits unspecific to any part.

Now’s a good time to remind everyone that with each new layer to the editor, there is a steeper learning curve for new players, so simplicity is a major factor to consider at all times. It’s always important to review what we already have and consider if more is yet needed.

New players will always want very little on their plate, so that they can get a tentative taste for what is to come, old players will want more and more, as they’ve already enjoyed much of what is available.
With new features, you must consider this balance, and try your best to uphold it. This is why many games gradually introduce new features and forms of customization as you progress, and is a big reason behind my designs for the unlocking system. Difficulty options too, can serve well for this purpose.

Thank you for taking the time to dig through these concepts! It’s always excellent to review what we’ve gone over, and further solidify our concepts as a result.


Guys, we need a finished plan for toxin customization! With the endosymbiosis done (and me tacking day/night issues next) it might be just a couple of weeks until I get around to this and will need a finished plan to be able to implement something.

I think the top 2 ideas at this point are:

  • Some kind of lock-key system to have toxin resistances you can evolve and compete with toxin producers to be locked in a race for better resistance / better toxins
  • Different toxin types that have different effects, like maybe debuffing ATP generation or movement speed or something like that

I will focus on this throughout the next few weeks. I think a safe option is going with a basic “various effects” sort of system, but I will try to think of a lock and key mechanism as another concept. Arms races as a whole will probably be important in the next few stages, so it’s a good idea to introduce a bit of that here.

Here is a proposal for a lock-and-key mechanic for agents.

Agent Rock-Paper-Scissors Mechanic

Toxins will serve as a dynamic, active threat to the player. Serving as an introduction to themes of evolutionary arms races which will be important in other biological phases of Thrive, this system introduces a layer of complexity to the game.

Prokaryotes v. Eukaryotes

Prokaryotes will have access to all forms of toxins, and will have limited means of developing immunity. This will make toxins very influential and powerful for prokaryotes, and a bit more like a traditionally rock-paper-scissors mechanic for eukaryotes.

Rock, Paper, Scissors Mechanic

Toxins will generally have three parts to represent aspects of agent warfare…

  1. Target - Characteristics that the toxin is more effective against.
  2. Scaling Factors - Environmental factors which can increase or decrease effectiveness. Represents resource availability/constraints.
  3. Inhibiting Factors - Traits which counteract the effects of the toxin.

The first aspect helps players know what to be wary of or what to target, depending on their or their competition’s composition. The second aspect helps players understand what the landscape of toxins in a particular patch might look like. The third aspect helps provide controls over immunity.

Toxins will damage all organisms, but will be more or less effective against certain organisms depending on certain morphological features and adaptations. Although players can tweak their morphology and utilize adaptations to counteract toxins, effective toxins will always be something to watch out for.

Type A, Heavy Metals:

  • More effective against organisms with sulfur respiration parts.
  • Affected by percentage of iron in patch. More iron % means more damage.
  • Inhibited by iron-respiration parts.

Type B, Herbicides:

  • More effective against organisms with photosynthetic parts.
  • Increases with increased temperature (capped at a certain temperature to avoid OP hydrothermal vent toxins).
  • Inhibited by adaptations to the mitochondria and chloroplasts, as well as cellulose membranes. More rigid cellulose membranes are more effective against herbicides.

Type C, Cytolytic Toxins:

  • More effective against organisms with more fluid membranes.
  • Damage increases with higher oxygen concentration.
  • Inhibited by increased rigidity for membranes.

This type of toxins will likely be a toxin that is effective across the entire microbe stage. It will have a pretty accessible form of immunity in the form of rigidity, but rigidity itself has some solid concessions needed from the player, opening up other concerns for the player.

Type D, Anti-Mitochondrial Toxins:

  • More effective against organisms with aerobic respiration parts.
  • Effects mitigated by sulfur contents in a patch, and lower temperature areas.
  • Inhibited by sulfur and nitrogen-processing parts. Inhibits growth of your organism.

This one is based somewhat on cyanide. It will have steep energy demands to portray the immense amount of adaptations required to maintain homeostasis despite possessing such a potent toxin, and will inhibit the growth of a cell (utilizes nitrogen).

Players will be aware of what is effective for and against toxins upfront; it would be a huge burden to place on players to figure this out for themselves.

Overall, players will likely focus more on toxins type C & D later in the Microbe Stage, as well as type B. Type A will likely be more present in the earlier Microbe Stage, and might dissipate in presence overall as the player and the planet progresses unless they evolve in deeper patches.

Other Adaptive Traits

Some upgrades or adaptations can also mitigate general toxicity effectiveness.


Certain membranes will reduce or outright cancel external toxin damages, necessitating more intrusive forms of delivery. Endotoxins and toxins delivered through means such as the injectisome will inflict damage unaffected by membrane resistance.

  • Cellulose will be weakly resistant to external toxins.
  • Chitin will be moderately resistant to external toxins.
  • Calcium carbonate and silica will be very resistant to external toxins.

Upgrades & Parts

Certain traits will counteract toxin resistance.

Mitochondrial Adaptations - The mitochondria will have an upgrade which allows for greater processing of toxins as a whole in exchange for total energy production. Cells won’t be able to absolutely mitigate toxins through this single avenue, but in combination with other parts, can create a formidable immune response system.

Chloroplasts can also be given certain upgrades to provide adaptive measures against agents.

Mucilage - The amount of mucilage you have stored in your organism will slightly reduce the effect of toxin damage on your organism, due to the slime somewhat reducing the permeation of harmful agents. This will provide some sort of option for prokaryotes besides fully transforming your morphology.

Part Composition - Since toxin effectiveness is dependent on player composition, players can make morphological changes to foster immunity.

(Pending Implementation/Acceptance) Surface Area and Volume Ratios - Certain toxins can be more effective for lower ratio organisms, while other might be more effective for higher ratio organisms.

Ultimately, I think agents will be something that requires a good amount of feedback and playtesting to get correct and balanced results. We can ultimately think about different target, scaling, and inhibiting factors to get a different risk layout if improvements are needed.

What is needed to be established in such a system is:

  1. A type of toxin that the player should be wary of, and should not be able to easily adapt to.
  2. A mechanism for the player to atleast counteract this primary toxin, and somewhat dismiss certain toxins.

With proper balancing, that can be done. And if nothing else, a much more simple “toxin A with A effect, toxin B with B effect, etc.” can work as well.


Hi! Theory team here, I will try to add some comments, though I am not a toxicology experts by any means :sweat_smile:

For what I have been reading (Bacterial iron homeostasis) the iron(-induced) toxicity in bacteria is, mainly, caused by an increase in ROS (Reactive Oxygen Species), which is of course a big deal, though also applies to eukaryotes. Indeed, from the 60’s up to the 80’s the medical community thought that the aging process was exclusively caused by ROS in mitochondria. Turns out there are more factors that affect aging, this is just to show how dangerous ROS can be.

That being said, I think that the most iron-induced ROS should occur in organism containing Photosynthesizing organelles, Oxygen Respiration organelles or both. Concepts like pH regulation, controlled gene expression and GSH (!! Last one is a very relevant biomolecule) can counteract it.

Other heavy metals do also cause toxic effects. I think that the top of the list are Lead, Gold, Copper, Mercury, Cadmium and Aluminum. Though from what I know, heavy metal toxicity is usually related to metal clusters entering the ECF (ExtraCellular Fluid - i.e. Blood), so I don’t know how these may affect unicellular organism. I have found this paper on Bacterial adaptive strategies to cope with metal toxicity.

That should be a way to go. Although, I think that heavy metals toxicity may arise again when dealing with higher-eukaryote’s diets.

Once again, I’m no expert, but… I think that Herbicide is a word that has meaning in human language, I mean, there is no “biological” definition of a Herbicide, it is everything that can kill plants, there are actually some herbicides that consists of spreading (entire) microbes on the field. I think that this could work if the hypothetical player’s world has plants, else it completely looses its meaning.

Cytolytic Toxins may also be called Cytotoxins. Penicillin could be described as such (though it is technically an antibiotic). Usually they are polypeptides or proteins.

I like a lot this idea.

Membranes are a very very important part on toxin resitance, but remember that cellulose, chitin (, hypothetically calcium carbonate), gram negative and positive schemes are there because there were toxins and enviromental conditions that lead into the evolution of those. It would make little sense to develop a membrane resistant to a toxin that an organism has never encountered (even though this could happen randomly, I think that the chances are sufficiently low to say that it’s not a norm).

I think these are great ideas.

Scientific Remarks (I guess?)

All toxins are products of secondary metabolism pathways. This implies quite a lot of things. First, an organism should be able to regulate the production of a toxin, both in order to not get auto-intoxicated and because usually these consume a lot of energy and because an organism that is producing toxins when there is not enough energy to maintain homeostasis would quickly become extinct.

There are a lot of secondary metabolism pathways. From what I know toxins can come either from (poly)peptides (or even non-proteinogenic amino acids) or related to alkaloids (usually) (or terpenes (rarely) ~ endosymbiosis could play a major role here).

Maybe I’m saying this because it is what I am currently researching but… I think that Ion Channel related toxins are very important, as they deregulate the homeostasis and cause a lot of damages, these are related to a lot of major “nowadays” diseases.

G-Protein related toxins are also important. I am sure that at some point in the game G-Proteins will be added.


  • Producing toxins is energetically demanding and should only occur when there is an excess of ATP
  • Peptides, alkaloids and terpenes are important biomolecules and metabolites. Each having its own metabolic pathway.
  • Ion channels (Voltage and Ligand Gated) + G-Proteins are important
  • The action of a toxin is not dependent of the synthesis process, very similar molecules can have completely different reactions on the same organism
  • Homoestasis is very relevant, pH regulation, gene expression control and GSH are important

Probably someone has already pointed out, but bacteriophages were, are and will be very important in bacterial evolution. They could be treated as toxins (as well as other viruses) at the microbial stage.

Again, I am no expert. I know a bit of secondary metabolism, but mainly organic synthesis and metabolic pathways, so don’t trust me blindly. If you have found any information about anything related please send it to me so I can take a look.

Hope the comments are useful!


Alright, so it is a doable thing to create toxin variants that are more effective against different types of cells.

I can work off based on that assumption to get started on the code needed to make it possible to fire different types of toxins in the future. We might also need to have the “default” toxin type changed as it requires oxygen to produce so when in the future there isn’t oxygen yet at the start of the game toxins wouldn’t be able to be made.

One big design decision I think that needs to be made now is that will we keep oxytoxy / another general toxin compound, or should each toxin have a separate compound? For example we might have about 5 or so different toxin compound types in the future (any more than that is not going to be possible to show with the current GUI) that can be produced separately and fired with their different effects. Or alternatively we could have just one toxin compound and each toxin vacuole when firing would “convert” the toxin to their selected toxin type on firing. In terms of producing toxins that’s going to be less flexible, but allow many more toxin variants without causing GUI bar display issues.


I see what you are going for here with the potential targets you have chosen, and I like the idea from a gameplay perspective. It’s good design, but I feel it moves a bit too far away from the realm of realism.
It might also lead to some unconventional situations when it comes to having things so specific. Be kind of funny to see photosynthetic cells evolve away from photosynthesis in response to a heavy “herbicide” presence. I doubt that would happen though.

This is honestly the one thing that I’m mostly iffy about. A good idea in theory, but I feel that in practice it would take things just a step too far into too complex territory. Strengths and resistance to the toxins alone should be sufficient in providing an engaging experience. I do admit that being able to ascertain what type of toxins might be found is an excellent idea though…
The same goes for some of the interesting debilitating effects of keeping the toxins you propose for things like type D’s growth inhibition. I believe we should withhold something like this until later if we feel it’s needed.

To me, a large part of what makes toxins potentially interesting is the wide variety of effects they can have on an organism. So differentiating what they do is a major part of the design. It also makes adapting defenses against them more interesting as well! That extra flagellum could be great, but the higher metabolic cost could make you more susceptible to inhibitors… Picking a poison to use is equally meaningful, as you’ll need to consider the types of predators and or prey you are contending with. And of course, you still need to consider the cost of producing the toxins and whether it’s worth it.

In the world of biology, toxins are incredibly diverse in form and function, but toxins utilized by unicellular species typically target more generalized systems of a cell (Even if they can be very specific to how).
This can include disruption of the ion channels in the cellular membrane which forces the channels wide open (or closed), leading to cell lysis. (In later stages these could primarily function as neurotoxins). Disruption of the metabolic pathways in organelles such as mitochondria. (Cyanides). And even direct reaction with the molecular integrity of the cell’s membranes, directly leading to lysis. (Necrotoxins/cytotoxins).

I feel like this already gives us some interesting effects to work with! So I’ll go over a simple trio of gameified toxins based off of real toxin varieties.

Toxins as they are currently implemented in Thrive easily fall under the category of cytotoxin. They do direct and immediate damage to the cell’s membrane. They are energy intensive to produce in meaningful amounts, and may not be as effective as a defensive endotoxin. Cell walls and extracellular coverings can be an effective form of protection against them.


  • Expensive to produce.
  • Immediate and meaningful damage.
  • Temporarily slows/disables healing.
  • Efficacy reduced (but not fully negated) through digestion and cell coverings.

Ion channel inhibitors, such as neurotoxins, are a slower acting toxin that can disrupt a cell’s ability to transfer ions through their cell membranes. For single cells this typically disrupts their ability to osmoregulate, but in later stages this could cause paralysis as it disrupts neuron and muscle function.
These toxins can be less metabolically intensive to produce, but may need to reach a certain level of dosage in a cell in order to yield meaningful results. This can make them great as a defensive option, or for selective predators that use it to slow down their prey for easier capture.

Channel Inhibitors:

  • Very little direct damage.
  • Cheaper to produce.
  • Temporarily increases osmoregulation cost of a cell. Not immediately lethal.
  • Higher energy production ceiling can allow cells to survive greater dosage.
  • I’d be down for rigidity somehow helping to resist this too.

Metabolic Inhibitors are a diverse group of organic and inorganic compounds that work similarly to membrane channel inhibitors. Despite the diversity, poisoning tends to specifically target mitochondrial metabolic pathways. Due to this, cells are forced to rely solely on alternative pathways to obtain their energy, or die. Deus already went over these, so I’ll just provide my own angle.

Metabolic Inhibitors (Anti-mitochondrial toxin)

  • Expensive.
  • Can become lethal much more quickly than channel inhibitors.
  • Ineffective against anaerobes.
  • Resistance can be developed through alternative metabolic pathways. (Mitochondrial upgrade).

All toxins should do a little bit of direct damage, for sake of “impact” that lets players know they are having an effect, it also makes it easier for the AI to realize something is up without the need for any additional behaviors. Ideally, we would also implement a visual effect to indicate that the cell is under the effects of a toxin.

For the player, that could be their health bar and/or ATP bar flashing purple depending on what is being affected.

Personally I agree that the best option would just be using the toxin compound as a catch-all for all variants. It’s just easier for developers and players both.

Sorry if this post is a bit messy and rushed, I just wanted to leave some potentially more grounded toxins on the table.

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It’s starting to look like I have next week free to work on toxin customization before 0.6.7 release. So I can probably fit in a couple of toxins with simple alternative effects. Any ideas what I could put in? My immediate ideas are like: membrane calcification agent that removes base movement from hit target, ATP production debuff that removes 50% of the target’s ATP production speed, or toxins that deal double damage against specific membranes / species that have a specific organelle / don’t have some organelle.

Those would be the kind of easy toxin customizations that could be done in a week (though I’d really only have time for a few not dozens, and that wouldn’t include separate toxin compound storages for the different kinds).


Toxin for membrane calcification and ATP reduction are must haves I think, and i guess having toxins that are strong against membranes that prevent engulfment could be nice (to have a way to kill these creatures without engulfment).

I don’t really think we should add more than a few variants at the start without having a specific purpose in mind for them (at least currently)


@rsaavedra Thank you very much for your input! Though it seems like design has pivoted away from the initial proposal, you’ve highlighted very important resources.


@Buckly I agree with you saying that it would be better to diversify the effects of toxins rather than just having them deal damage at a varied scale. Though I do think that toxins are inherently one of Thrive’s more gamey mechanics since the way they are implemented is a pretty abstract representation of how they function in real microbiology, especially for prokaryotes.

One thing: I think channel inhibitor toxins as you describe probably wouldn’t be utilized much since it would be really hard for the player to understand exactly how much of their toxin is needed to visibly effect prey. Perhaps having it be a flat and easily noticeable impact, such as Hh’s suggestion of a flat rate, would be better.


@hhyyrylainen I think those are pretty good effects to go with for now, providing a pretty interesting variety to deal with. I can think of a few more currently, but since you’re going on break soon, it’s probably best to start small as @Titan said.

I would like to mention that I don’t think we should have toxins targeting specific types of membrane since the whole point of several membranes is a trade off between defense and offense. If we make toxins specifically tailored towards specific membranes, I feel that kind of beats the point. The challenge with some membranes and toxins is figuring out ways to deliver toxins to them rather just putting a specific effect on - thus making toxin pilus useful in the future.

I think for now, we can go with this list:

  • Calcification Agent - Removed base movement from hit target (5 second max, can be reduced by membranes). Countered by flagella.
  • Channel Inhibitor - Provides a flat ATP production debuff (50%, though balancing might require changes). Countered by increase membrane rigidity, which reduces strength of debuff.
  • Metabolic Inhibitors - A toxin that is more effective against mitochondrial and metabolosomic organisms, less effective or completely ineffective against anaerobic organisms.
  • Antiflagellan Toxins - Temporarily stuns flagellum (5 seconds max, reduced by membranes). Base movement remains.
  • Cytotoxins - Currently implemented. Defensive measures, such as membrane resistance strength, could be reexamined.

This is a pretty solid array of effects which could lead to some really cool arms races down the line. I think these should generally be sufficient for toxin effects for the microbe stage as well, with other additions being a bonus depending on how we want to alter mechanics.

Perhaps another effect could include a toxin that targets chemoreception, which causes other organisms to not respond to threats and not respond to prey. For the player, the screen can be dimmed and blurred on the outer edges.

Another note: I think the mobility related toxins should have a slight cooldown, so to prevent players being completely stunned with no means of evading danger. It doesn’t have to be long - perhaps a second should be good to allow the player atleast a chance to respond.


I think it’s worth doing a serious rebalancing of membranes with a more in-depth toxin system, so I’ll try to post something soon discussing that.


That’s fair. My intent was for a toxin primarily intended to reduce the motility of prey/predators by reducing the available energy. And of course, it would eventually have lethal consequences if you had a high enough dosage. Having more excess ATP generation would allow you to overcome more and more of it.

You make a great point about it being hard to gauge the vulnerability of a cell to this, as you would have to pay close attention to how many energy generating parts they have and calculate that in your head! Haha.

I’m not entirely sure about the name of the “calcification” toxin. The name you are looking for might be Macrolide toxins. These are actin inhibitors that disable a cell’s motility. On Earth, they are produced primarily by bacteria to inhibit the growth of rival colonies, but they are also produced by various species of sea sponge for defense. Other than that; I like the idea of the toxin itself, mechanically.

We might actually have to drop this toxin with the other mobility inhibiting toxins now also on the table. Unfortunately reducing ATP production is just going to either kill a cell outright or just do what the other toxins do.
But… What if we combined the concept with the antiflagellan toxin concept?

Perhaps channel inhibitors could instead limit the amount of ATP a cell can produce to the amount it consumes. The idea is that it would force cells to “limp” for a bit.

Otherwise, I would just give the name to the antiflagellan toxin. Though the name does convey what it targets pretty well… Hmm.


Good point actually. If nothing else, I think offering those multiple options of doing roughly similar things gives the player multiple ways of approaching and countering toxins due to the different targets and adaptations necessitated. Though since again the effects would be similar regardless, it might be worthwhile to just buff the ATP effect enough for the “stun” to work, and think of atleast two other effects to implement.

So I guess for now we approach the motility related effects through that ATP-lense and think of atleast two other effects.

Also wanted to note: slime technically is an agent as well! It might be worthwhile to think of a way that cells might counter the entrapping effects of slime, such as maybe adaptations to the cilia. That could result in cool entrapping mechanics.

What would this mean technically? I’m trying to imagine how this would be implemented but I’m not coming up with anything feasible. That is because the cells don’t know how much ATP they need, they just generate ATP if the ATP storage is not full. It’d be much easier to disable flagella or base movement, those are like at least 5-10x easier features to make.

I just wanted to mention, as I don’t know to what extent this has been discussed, that creatures should have a suitable way to respond and adapt to the various toxins.

We should try to avoid a situation where the player gets constantly stunned or killed without having a possibility to adapt defenses. These shouldn’t completely invalidate the threat of predation mind you, but should be effective enough that there is a possibility of survival.

For example certain membranes or organelle upgrades can be evolved to lessen the effect of ATP production inhibiting toxins, but these should be tradeoffs of some sort, and again, not completely eliminate the threat (leaving the possibility of extinction open)

I would also like to mention that there should be a soft limit on how many toxins (and how much) an organism should be able to use, to prevent strategies like stunning your pray and immediately killing them with toxins. (Too easily) This doesn’t mean that this strategy should be impossible to pull off, just that it would require a lot of effort and be balanced so it’s not too op (for example limiting the rate at which toxins are produced)

Your organism should be very specialised in this type of predation to pull this off effectively.

Touching on one of the points above, stunning your pray for example shouldn’t be as simple as clicking a button once. To effectively stun your prey you should hit them a few times or deliver the toxin via injectisome.

Finally there’s also the adaptations that would allow you to protect yourself before coming in contact with toxins in the first place. So this would be flagella to outrun predators or chemoreceptors to detect them. Players should be aware of these possibilities and maybe we should investigate other such adaptations (some sort of lure or decoy abiliy by upgrading the signaling agent perhaps)

This is also very interesting, slime is an offensive as well as defensive tool, and having adaptations to deal with entrapment is important. I’m also not a fan of the current system, where any creature with slime jets is not affected (as far as I know at least), instead adaptations to cilia or maybe having to use slime for example would be better in my opinion.

(Also btw I’m writing this on my phone so sorry for any mistakes)