Compounds and Compound Toxicity

There’s still some tweaking that can be done regarding Thrive’s compound system that would really spice things up in terms of gameplay – some tweaks rather simple, some requiring systems that are yet to be implemented into Thrive. On the one hand, there’s a wide variety of elements, nutrients, and molecules that a cell needs, meaning a lot of room for expansion from the few elements utilized in-game already; regarding this variety, the question is what biological realities would be desirable to add to the game, as there isn’t really a way Thrive can simulate every single compound’s effect on a cell without stretching itself thin. On the other hand, the way cells have evolved to cope with new compounds that are initially damaging in the Earth’s developing atmosphere – how cells responded to increased oxygen levels, new available nutrients from runoff, etc. – is an important part of our evolutionary story and would be a very engaging aspect of Thrive if properly implemented.

Concepts for the first idea (new elements) are as complex as deciding on the impacts of new environmental compounds, their behavior, and how they impact the player. Concepts for the second idea (essentially, compound toxicity) are more tough, as I think they depend on a good upgrade system. However, even more difficult is the fact that said upgrade system would probably operate differently than the simple(ish) organelle upgrade system. Whereas I don’t think there should really be a limiting factor on the way you tweak or upgrade your organelles besides MP cost and what would be best for your cell since we don’t really see such “arbitrary” limits in real evolution, I do think I player should have to make a choice to compromise their cell’s immunity to the wide array of environmental compounds a cell sees. In other words, players should have to pick what elements they want to become immune to or specialize around. No living being is immune to everything, you know? No living being is perfectly calibrated to take advantage of every single environmental factor. Plants are perfectly adapted to withstand sunlight, but can be poisoned from other elements. Extremophilic cells can adapt to withstand intense pressure and “traditionally” poisonous elements such as hydrogen sulfide, but might be sensitive to light or oxygen, because those factors might not be present in their environment so they would have no reason to build up that immunity. And if they did build up that immunity, they wouldn’t really be in an environment where they would need immunity from the hydrogen sulfide and smog, would they? Also, from a gameplay perspective, what fun is it if a player could get every upgrade possible regarding immunity and just float through every unique environmental challenge with ease?

There are also various unique aspects related to organelles and other questions to ask. If we make oxygen toxic at the beginning, do we hide metabolosomes and mitochondria at first from the player since they would be ineffective or impossible? If so, how do we make them unlockable, and what other part would help the player in the meantime? How do you implement the trade-off system?

I previously attempted to make a concept for this part of the game revolving around enzymes which I feel like had some good ideas, but because it required a mechanic that might not be extended to other components and features of the game, it had some weaknesses (Enzyme Concept). So I’ve been thinking a bit and have a few suggestions regarding compounds and compound toxicity.

New Compounds/Compound Tweaks that Should be Considered

Potassium – An “environmental” compound that can increase the speed of evolution. Provides a MP discount in cell editor that scales based on amount of potassium available OR reduces amount of ammonia/protein required based on amount of potassium available.

  • Scientifically, a potential contributing factor to the Cambrian Explosion might have been the increased availability of potassium in the oceans due to increased land runoff.
  • Potassium could naturally be more present and fluctuate more near the shoreline or in rivers, thus providing a unique incentive for cells to migrate there.

Smog/Smoke (Carbon Monoxide?) – A cloud compound present in the hydrothermal vents or in other parts of the environment during a natural disaster which damages cells.

  • Can uniquely characterize the hydrothermal vent patch, providing an aspect of the environment which the cell must avoid.

Compound Toxicity/Immunity Suggestion

Function: Have various sliders in the cell editor which denote the presence of enzymes. Each slider will have a left-most point, which denotes an absence of said enzyme, a point somewhere in the middle, which denotes an adequate enough presence of said enzyme to provide immunity (perhaps the location of this point doesn’t necessarily have to be in the exact middle based on how “easy” it is for real cells to adapt immunity to this compound?), and a right-most point, which denotes the presence of adaptations which allows the cell to take advantage of said compound. If you place the slider on the left of the midpoint, you will experience the negative effects of the compound. If you place the slider on the midpoint, once again, you won’t experience any negative effects from the compound. And if you place the slider somewhere near the right of the midpoint, your cell will in someway benefit from the presence of the compound in the environment.

Trade-Offs: The farther right the slider goes, the more ATP it will take to maintain those enzymes. For example, let’s say we make hydrogen sulfide toxic to the player without an adequate enzyme buffer. To the left of the midpoint, the ATP generating capacity of your cell is reduced the more hydrogen sulfide your cell takes in, risking your cell to start “choking” to death if enough ATP generation is compromised. Sliding it to the midpoint would create a basal amount of immunity, enough to put on hydrogen sulfide organelles, and sliding it to the right would enhance the function of those organelles. But the more you slide the sliders to the right, the more ATP is needed to be constantly burned to keep these functions up.

With enough sliders, this means that the player would have to choose between various enzymes that take ATP; maxing out or even making your cell immune to all compounds could be done, but why would you want to reduce how much ATP is available to your cell for other important options? Why would you keep an immunity to hydrogen sulfide near the surface when it isn’t present and when you could use ATP for other important parts?

Questions to be Addressed

Something I noticed is that you’re basically guaranteed to adapt around certain compounds. For example, you’re going to eventually want to protect yourself against UV-Radiation (light) or oxygen if you want to go to the surface. As such, should those compounds be included in this slider concept, or should upgrades revolving around oxygen toxicity or UV-light be integrated into another upgrade aspect of the game?

How applicable can this concept be to other parts of the game? For example, I can see immunity against biological poisons generated by other cells benefiting from a similar system, but besides that, what else? And how far ahead would this enzyme system be applicable? How will you tweak enzymes in the future when you’re a macroscopic organism? Should this concept stay the same throughout that period of time or should it transition to another more simple upgrade system by then? And if the latter, why even have this system?

What parts of significance would you use in your cell if you don’t have immediate access to aerobic organelles since oxygen would be poisonous? This isn’t necessarily an issue limited to this concept, but a general one.

What about those organelles, such as thylakoids and metabolosomes and chloroplasts and mitochondria, that revolve around the compound you’d have to be balancing out? Would you be allowed to place these parts if you don’t have proper immunity? And if you suddenly remove a specific immunity, what happens to those parts? For example, you move from the surface with light and chloroplasts to the deeper parts of the ocean with less light, thus removing the need for an immunity to UV-radiation. When you go to your sliders and remove the enzymes responsible for light immunity, do chloroplasts and the sort just stop working?

Balancing would also be an issue; would the benefit gained from light-based immunity compound to the point that you could just adapt more compound immunities? And also, since you’d be penalising the player by increased ATP function, how much can increasing your immunities to the point of benefit really benefit the player?

Questions like these make me thing that A.) oxygen and light should be treated differently from other compounds and B.) some other “currency” other than ATP must be used to limit the sliders, similar to my earlier enzyme system.

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Sounds great, the UV stuff might give people the reason to not rush for the top.
And the new compounds sound intresting too.

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I don’t know how often this happens, but in 2 of my thrive playtrougts there were cells that brought hydrogen sulfide from hydrotermal vents to the surface patches

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I think that makes sense initially, and it’s a pretty cool thing to see. Cells obviously don’t immediately get rid of excess; vestigial parts were an important aspect proving the validity of evolution. But eventually for realism’s sakes, those parts should be selected against.

I typed up something very much based on @Buckly’s post on the development forums (Environmental Tolerance Adaptations - #23 by Buckly - Gameplay - Thrive Development Forum). It runs with a concept Maxonovien proposes. I’m sure they have thought of it in someway already, but I just wanted to type it here to help map out how it can effect the game.


CONCEPT FOR COMPOUND TOXICITY

Oxygen

Problem: Oxygen is actually a dangerous compound to many organisms, as it can significantly damage cellular metabolism by creating oxygen radicals, which alter molecular shape – catastrophic for microscopic cellular components. It is generally believed that early life had a low tolerance for oxygen, resulting in the Great Oxygenation Event; a point in our Earth’s history where, when oxygen surged as a result of photosynthesis, a massive extinction event occurred. However, once oxygen was widely available and cellular respiration/metabolism adapted, the energy potential oxygen provided was immensely beneficial for life, kickstarting a more rapid pace of evolution.

What this means for Thrive: Oxygen should initially be poisonous to cells; at the same time, it should be an essential compound to be utilized on the way to enhanced metabolism later on, or in otherwards, a checkpoint. At the beginning of the game, organisms shouldn’t have a strong resilience to oxygen, which will effectively mean that most life will be initially limited to the deeper patches. Eventually however, some organisms will evolve enough buffering to oxygen to be able to make it to the higher patches. As photosynthesizing organisms pop-up (photosynthesizing cells don’t have to be entirely aerobic if they sufficiently expel oxygen produced at a rapid pace it turns out), the player’s planet will see a rapid influx of oxygen. At this point, oxygen will be very prevalent near the surface and will increase in concentration in even the deeper patches, meaning cells will be selectively pressured to adopt oxygen-buffering practices. After a sufficient amount of time passes and as oxygen levels out, due to adaptations in related organelles, a huge surge in metabolism will occur, increasing the speed of evolution and setting the path for eukaryotic and multicellular life to start popping up.

Questions to Answer

  • What negative effects will oxygen have on cells? As Buckly suggests, oxygen will basically be absorbed by cells. Negative effects won’t immediately occur, but once a critical point is reached and the cell can’t get rid of oxygen fast enough, ATP production will start taking a hit; the speed at which this point happens is dependent on the amount of oxygen present. If enough oxygen is accrued, your cell will essentially run out of ATP and die.
  • How do cells counteract this? Also as Buckly suggests, an organelle will be used to help enhance the rate at which oxygen is expelled from a cell. The metabolosome is the obvious candidate, but I think just being able to place one as they exist in the game currently is a cheap move and unrealistic. I suggest that metabolosomes (and other organelles) start out as very diminished versions of themselves. As you upgrade them, both the rate at which it dumps out oxygen and how beneficial oxygen is to the microcomponent’s function increases. Eventually, you should have what we now know as a metabolosome, which properly fufills aerobic respiration.
  • What limits a player from just bum-rushing a metabolosome? Nothing technically. If they wanted to, they could fully evolve a metabolosome to a point at which aerobic activity is prematurely evolved. But because oxygen wouldn’t be a major factor before the Oxygenation Event, certain upgrades after a certain point make no sense rationally. A jump from 10% to 25% aerobic respiration efficiency in metabolosomes won’t make much too much of an impact if the environment has only like 2% oxygen. As such, if an experienced player wanted to just get stuff out of the way, they could get those upgrades and still benefit in some ways. But for those playing the game at their own pace and for those reacting to what each playthrough offers, it wouldn’t make sense to just bum-rush metabolosomes when other things can be done with limited MP.

Concerns: This concept means giving the player less control and giving the environment more importance. Metabolosome progression, and thus, early metabolism will initially be limited since oxygen will start low. Currently I think this is a good thing; it’s realistic, and I don’t feel like the player is reacting to a changing environment in the current game, just to other cells. But it is something to keep in mind of.

The player will depend on the presence of photosynthesizing organisms to some extent, as they are the ones who triggered the Oxygenation Event in real evolutionary history. This can be remedied by having a hard-coded increase of oxygen in the game itself.

Furthermore, this can be customized in planet generation to dictate the pace at which the game of Thrive moves forward, similar to setting Game Speed in Civilization. Increasing the speed at which the hard-coded increase kicks in can quicken game pace, while having it be more based on the presence of thylakoid bearing organisms can lengthen game pace.


I think this is a very solid concept that is minimally invasive to the game’s existing design and with many desirable impacts. I also think another concept should be made for UV-tolerance and thylakoids (I assume they’d start out as UV-absorbing pigments) to map out the evolution of photosynthesis. I’ll cook that up soon.

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So I looked through the development forum and saw this thread (Passive Enzyme/Protein Slots System - #34 by Narotiza - Gameplay - Thrive Development Forum) with a concept for how enzymes would work. It basically has a sort of “slot” system where a player will have a certain amount of hexes they can place various enzymes in which do various things.

Different enzymes will have different characteristics which influences the way a creature looks or behaves: for example, membrane proteins benefit from more surface area (more membrane), so they’d want to be kind of long. Or cytoplasmic proteins benefit from more cytoplasm, so they’d want to be as large as possible.

I like this idea. It adds a soft cap on how many enzymes are equipped with the number of free hexes available to the player, meaning players will have to choose and make concessions for the greater good of their species. As such, the hyper-generalist murder machines we see in game today that make water bears look like earthworms will be no more – why would you keep a bunch of unnecessary environmental tolerances in your genome when you could use that space for more useful adaptations? It also is a pretty broadly applicable concept with many potential uses and future synonyms. Perhaps advanced behaviors, like hibernation or migration and such, can have their own genome slots to be placed.

I have a few questions and observations, however.

  1. The hydrothermal vents probably require their own enzymes to protect against the environmental heat and pressure. Knowing this, your genome is probably already going to have those two genes in your slots as soon as you start your game. Perhaps when you start out, you only have three genome/enzyme slots open – two taken up by “highpressurease” and “temperaturease”, one free. I think this allows an easy tutorial setup/ an easy introduction for the player to the tab. The two existing proteins will be explained, and then the player will be prompted to place another protein. Perhaps hydrogen sulfide can initially be damaging to the player, but placing a genome allows it to be synthesized. And then the player is prompted to place this genome onto theirs as an introduction.
  2. The extent to which this concept holds control over your cells adaptation and the way it interacts with the existing organelle system will have to be further defined. I think a lot of this will be made easier by creating the roster of enzymes/genes you can place, but what I mean is that I’m sure there will be overlaps in functions between organelles and genes, and that overlap needs to be defined. For example, say there’s an enzyme focused on oxygen tolerance/aerobic respiration. Metabolosomes already cover that aspect of the game currently. Do you need to place the oxygen gene to unlock metabolosomes? Or does the oxygen gene simply dramatically enhance the function of metabolosomes? Or does it add the aerobic aspect of the metabolosome’s duty? I think these are pretty easy questions to answer with enough thought, but they still need to be answered.
  3. A lot still needs to be drawn out surrounding the two most critical environmental adaptations in life’s evolutionary history: oxygen tolerance and protection against radiation from the sun. I think the current concept says that once a cell takes in too much oxygen/sunlight/whatever harmful compound, they will start feeling negative effects, and the player can counteract this by evolving ways to get rid of these stored compounds more rapidly, which sounds really fun. But what part of this evolutionary function will be represented by upgrading organelles and what part of this evolutionary function will be represented by placing a gene? Perhaps the gene significantly increases the rate at which metabolosomes interact/get rid-off of oxygen? Tolerance for the sun is a bit easier; I think having an enzyme which significantly increases tolerance for sunlight is simple enough.

Other than that, I think it’s a very good concept. Merry Christmas

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Buckle up folks, it’s a long one. Perhaps my longest yet.

I decided to spend some time focusing on this concept and since I felt it was almost there, but it just needed a bit of detail to essentially be game ready. There are so many concepts in this similar state - almost there, but not quite yet. So I’ve decided to focus on these concepts in an effort to help make Thrive great. So expect perhaps even more long posts. You’re welcome.


ENVIRONMENTAL TOLERANCES

Environmental tolerances can wildly vary across Earth, let-alone any sort of alien planet. Everything from sunlight, oxygen, pressure, salinity, pH, temperature, and any other environmental factor has a significant influence on the metabolism of organisms. In light of this, Thrive should focus on discerning which mix of environmental conditions to account for. This list of conditions will be as small as it can be to ease the burden placed on both the development team and the player, but large enough to introduce tradeoffs so that the diversity of life can be adequately represented.

I honestly think that for the Microbe Stage and for most of Thrive, we just need to account for 4 environmental conditions for a minimally-viable product…

  • Pressure: Influenced by the force – or lack of force – applied by the atmosphere and the ocean on a creature. In the deepest parts of the ocean, the pressure can crush an organism, while on the tallest mountain peaks, the lack of atmosphere might suffocate an organism.
  • Oxygen: Oxygen can screw atomic structures up, representing a danger to any metabolic system. Bacteria are oftentimes divided based on whether or not they are anaerobic or aerobic. Important for Thrive, as a significant evolutionary moment in the history of our planet involves the transition of biota from being accustomed to anaerobic environments to aerobic environments.
  • Temperature: Heat and cold will kill, but certain species thrive near underwater volcanic hydrothermal vents and in the freezing poles of the world.
  • Salinity: Saltwater can be dangerous to organisms unable to properly dispose of said salt, while freshwater can be dangerous to cells who are finetuned to maintain homeostasis in saltwater.

Note - I am a bit skeptical of salinity being necessary, but since it is such an important and universal aspect of cell homeostasis universally, I’ve included it; also, freshwater and saltwater life is an important distinction in life and microbiology. Some may also notice that I have neglected sunlight, which can be extremely catastrophic for certain unaccustomed organisms. But I feel that the other environmental tolerances I’ve listed will eventually effectively simulate the same sort of dynamics at play on Earth. By that, I mean that I think simulating things like oxygen content will naturally simulate the development of tolerance for sunlight, as creatures who are intolerant of oxygen will eventually be relegated towards the depths of the ocean just as organisms intolerant of sunlight would be. Because of that, sunlight tolerance might be adding too much fluff to Thrive, but by all means, we can quickly create a concept for that if it is deemed necessary.

Organisms deal with these environmental tolerances mostly through their morphology and through creating enzymes to combat extreme environments. The way organisms employ enzymes varies immensely, but in regards to environmental tolerance, the common trends are either…

  • Type A - Creating a bunch of an enzyme which creates things that in some way cancel out a harmful factor. Toxin-resistance works like this, but oxygen and salinity are the two environmental conditions also dealt with through this method. For oxygen, certain enzymes create molecules which basically cancel out excess and potentially catastrophic oxygen, and for salinity, certain enzymes create solutes which might blend with sodium.
  • Type B - Developing enzymes which operate best in “abnormal” situations, at the cost of producing enzymes which work best in “normal” conditions. So for example, cold-water fish utilize enzymes which operate best in colder temperatures, and thermophile cells use enzymes which operate best in high temperatures. Temperature and pressure tolerance works like this, with pressure-related enzymes creating proteins which can tolerate and work best under duress and temperature-related enzymes facilitating reactions. This effectively makes “ranges” of tolerable conditions instead of a flat “everything is tolerated up to this point” like in Type A.

The first type of enzyme is pretty easy to understand – the more of them you have, the more tolerant you are. The second one deserves more explanation, as it has more implications on the lifestyle of the organism since said enzymes work best in ranges, and are thus more consequential in determining habitable ranges.

Utilizing the second suit of enzymes, organisms generally display three levels of adaptations towards environmental conditions…

  • x-Tolerant: Species are unbothered by the presence of said environmental factor unless the factor is overwhelmingly present.
  • x-Philic: Species perform optimally in the presence of said environmental factor and are more tolerant to high levels of the factor, but still suffer from the most extreme of conditions.
  • Obligate x-phile: Also referred to as “extreme -philics”, obligates can only survive in the presence of said environmental factor, able to tolerate even the most extreme of conditions.

For example, lets look at pressure. Barotolerant organisms can tolerate high pressure more than the average organism can, but not to an extreme amount and generally prefer the absence of high pressure. Barophilic organisms prefer high pressure environments and have a heightened tolerance relative to barotolerant organisms, but still might not be able to manage the depths of the ocean. They also begin to operate less efficiently in lower-pressure enviornments. An obligate barophile, meanwhile, can only survive in the presence of high pressure, and perform very well in extreme environments, such as the ocean depths.

Furthermore, these different levels of affinity denote different levels of optimal functioning, and thus, different habitat ranges. Again, a tolerant creature still performs optimally in the absence of whatever it is tolerant to, so although it might have a greater tolerance, it is not completely specialized. A philic creature is adapted to the point of it preferring environments which have heightened environmental conditions at the cost of efficiency its normal habitats. And an extreme phile or obligate depends on a high level of an environmental factor to survive, suffering in more normal ranges. The chart below helps explain this…
image


APPLICATION TO THRIVE

Knowing this can make it easier for Thrive to simulate environmental tolerance. For enzymes correspondent to salinity or oxygen, it’s as simple as having different levels of tolerance which just add onto each other. And for the second type of enzymes correspondent to pressure it’s as “simple” as prescribing ranges of environmental compounds, developing a trait for each environmental factor and various levels of said trait representing a tolerant, philic, and obligate-level, and having organisms outside of their optimal zones have negatively affected ATP output.

Currently, concepts on the development forum show that these tolerances, and potentially other complex organism traits, will be addressed through a sort of “slot” system, in which the player will choose from various traits (represented as enzymes), limited by the space on the player’s genome. Demonstrated in this concept:

Such a concept presents an ingenious method of dealing with environmental tolerances and other complex considerations evolution must oftentimes account for. You can spend points to unlock a tolerance, and then upgrade that tolerance into whatever level you desire. Environmental enzymes can have upgrade levels. The first type of enzymes (the more you have the better tolerance) are pretty simple to represent, with an upgrade simply increasing the amount of tolerance you have. The second type of enzymes (different concentrations indicate different habitable ranges with tolerant, philic, and obligate levels) are just a bit more difficult to understand, but different upgrades will basically indicate different patches your organism can live in. So a level 2 pressure organism (barophilic) would prefer living in a certain range, a level 1 barotolerant organism would prefer a certain range, etc. The more upgraded your protein, the more slots it takes up in your genome – so players are encouraged to pick and choose what they want to be.

At this point, I think the concept is robust and basically perfect for the microbe stage, but then I think we start running into problems when we consider the future stages of Thrive. I had a certain amount of it thought out with what I think is a cool idea, but it left me in a predicament that I wanted some feedback on. Let me explain.

THE PROBLEM

I first bumped into a bit of the problem when I considered the fact that certain traits are basically going to be always selected on most playthroughs. For example, with oxygen-tolerance being an enzyme-related tolerance, at a certain point, the player will place the oxyenzyme down and never take it off unless they want their species to go extinct or be relegated to the depths of the ocean, which might be bad news for progression. So that basically means that a certain amount of slots will be constantly taken and the player will pay no attention to the concept in the later stages as certain environmental factors become stable. Then I thought about mitochondria and how they kind of imply and rely on the oxyenzyme, which opens up a can of worms – are mitochondria conditional only to organisms who have that enzyme, and are they greyed out without that enzyme equipped, etc. etc. But then I looked further and realized that many environmental tolerances will run into a similar situation. The high-pressure enzyme overlaps with shells and compact morphologies and things like that, the high temperature enzyme overlaps with scales while the low temperature enzyme overlaps with fur, salinity will overlap with morphology of gills, and all that sort of stuff.

A SOLUTION

Basically, certain morphological traits or parts will come with their own environmental tolerance buffs/detriments which modifies the amount of space an enzyme takes up in your genome. For example, consider oxygen and metabolosomes/mitochondria. We’ll say that the metabolosome comes with the level 1 effect, an upgraded metabolosome comes with the level 2 effect, and a mitochondrion comes with the level 3 effect. If you place a metabolosome, you automatically get level 1 and your oxygen-enzyme shrinks by 1. So level 3 would take up 2 slots now, and level 2 would take up 2 spots. If you place an upgraded metabolosome, your creature automatically becomes aerophilic, and level 3 would take up 1 slot now. If you place a mitochondrion, your creature automatically becomes an obligate aerobe, and the oxygen enzyme won’t be accessible in your gene library.

This frees up space in your gene library for other enzymes to put in. So if you were eyeing to expand your capabilities of tolerating high pressure environments but couldn’t before because the oxygen enzyme took up too much space, now’s your chance. But keep in mind that these statuses are dependent on the parts in your cell/organism – if you remove a mitochondria or upgrade it in a way that makes it less aerobic (as some eukaryotes have), you might lose a level of tolerance. You can apply the same concept to various parts – gill upgrades in the future will deal with salinity, fur and scales will deal with temperature, armor and compact skeletons will deal with pressure, etc. etc. Keep in mind that a player should ideally also want to place upgrades not related to environmental tolerances on their organism, so they’ll be incentivized to eventually seek out morphology instead of a more artificial genome as answers to their situations to free up more cool adaptations.

ANOTHER PROBLEM

Another problem shows up with this solution, however, in a thought experiment regarding the later stages – a player or organism who only uses their genome and not their morphology for whatever reason, resulting in out of place creatures and obtrusively artificial game restraints. Say you as a player edit your morphology in the aware stage to become accustomed to the extreme oceanic depths. You make your skeleton compact at the cost of size, you slow down your metabolism a bit in an effort to deal with a low-resource environment, you reduce your surface-area volume, all the good stuff. You do everything you should and everything that is realistic to deal with intense pressure, making concessions so you achieve the playstyle you are fascinated by. But then, you look around and you see a fat, quick, and gigantic creature that looks extremely out of place which absolutely creams the competition seemingly unbothered by the constraints its environment places on it. Of course, the player would be confused, until they examine the genome of the creature and realize that it gets by just through its enzymes, having a level 3 pressure tolerance – a very cheap trick, and very unrealistic.

Multicellular creatures are capable of more easily visible and complex adaptations, such as fur or scales or a condensed body plan or whatever else to deal with its environmental factors, but a unicellular creature depends on invisible enzymes and proteins and genes to get it through harsh conditions. And the passive enzyme concept accounts for this, allowing players to make cells adapting for harsh environments that isn’t placing enzymes, which as mentioned before isn’t really ideal. But when we start arriving at the point in life’s history where morphological features are what indicates environmental tolerance, what happens to the passive enzyme concept?

Part of the reason that enzymes become less potent is because as organisms become multicellular and develop specialized tissues, it becomes a lot harder than just developing an enzyme to ensure environment-proofing. With all the coordinated tasks going on in a multicellular organism – a circulatory system, a nervous system, muscles, etc. – morphology has to be utilized much more and alongside enzymes to adapt to harsh environments. For example, deep sea fish have proteins composed of a more durable substance than other fish, but even that has its limits – beyond a certain point, severe morphological concessions have to be made to the point that it is made extremely rare for vertebrates to be found in the depths.

ANOTHER SOLUTION

There is one way of dealing with this that’s pretty simple, based largely on the above train of thought and existing concepts. NicktheNick mentioned having certain enzymes scale based on certain characteristics of your cell – so for example, an enzyme which can boost cell metabolism based on exposure to the sun would work best with a cell with maximal surface area, meaning the player would want something with a lot of cytoplasm exposed. Along the thoughts of this idea, we can simply have certain enzymes dealing with environmental factors weaken as your organism grows in size, and have that weakening be made so that by the time you are comfortably multicellular, a level three tolerance would effectively be equal to a level two or level one tolerance. So if players want their advanced multicellular creature to live in the depths, simply playing with your enzymes like a cell won’t get you there – you’ll need to make morphological changes to adapt to the environment.

And of course, not every environmental compound should scale with size. I think only the environmental factors corresponding with enzyme type B (the whole tolerant philic obligate thing) should scale with size, so specifically, pressure and temperature enzymes. Things like salinity and oxygen enzymes don’t really scale off with size.

The same can be said for the effects of certain traits – as your creature gets more complex, perhaps the type of membrane you have will become less influential, so you can’t just assume that your calcium carbonate will take you all the way to the multicellular stage unaffected. Then, you’ll have to evolve a more advanced trait, perhaps taking advantage of your eukaryotic capabilities, to reach the depths. The whole idea is to make it so that what works for simple unicellular cells is different from what works with complex multicellular organisms, and I think this does a good job of that.

And with that, I think we have a robust concept.

With all that being said, here is a basic outline of the previously mentioned environmental tolerances, their levels of affinity, and which morphological features act as permanent status buffs conditional on placement…


TYPE A ENZYMES (FLAT UPGRADES)

OXYGEN: Very important to simulate the Great Oxygenation Event, but becomes a bit irrelevant in the later stages as most life gets mitochondria and the environment becomes more stable.

“Normal” Range – (Assuming oxygen will start off below 1 percent?) The default organism will be anaerobic, as life was in its early history. Any decent presence of oxygen will impact your creatures metabolism, which won’t be a factor in the early points of your planet’s history, but as oxygen-product photosynthesis develops and slowly transforms your planet’s atmosphere, could relegate your organism to the depths of the ocean.

Level 1 tolerance indicates an organism that can tolerate small amounts of oxygen (up to 3%), allowing it to deal with early cyanobacteria-dominant environments while being able to maintain metabolism in an environment devoid of oxygen. Takes up 1 genome spot.

Level 2 tolerance indicates an organism acclimated to heightened oxygen content in the atmosphere (up to 10%), and indicates that said organism performs optimally in the presence of oxygen – however, very high oxygen contents still remain potent. Takes up 2 genome spots.

Level 3 – Level 3 tolerance indicates an organism fully adapted on oxygen, able to fully utilize oxygen in its metabolism to generate immense amounts of energy. Takes up 3 genome spots.

Parts Which Help – Metabolosomes and Mitochondria will offer tolerance buffs, and I am assuming that metabolosomes will eventually be built up to through upgrades since oxygen will not be present in the first few generations in a Thrive playthrough. Metabolosomes will offer level 2 tolerance, and mitochondria will offer level 3 tolerance. It just serves to get the oxygen enzyme out of the way since it will basically never be altered again after a certain point. Certain upgrades to the mitochondria, such as a specialized organelle I forgot the name of which functions through anaerobic respiration, can alter the buffs offered by the part perhaps.

Things to Consider – I think this is a very good concept because it brings in the anaerobe-aerobe dynamic in Thrive. Being an obligate aerobe is kind of implied already – if you have mitochondria and metabolosome with no oxygen, you won’t generate enough ATP as a complex cell because your most powerful organelles are useless. But obligate anaerobes haven’t been represented in Thrive up to this point, which becomes a pretty important distinction in phylogeny and taxonomy. With the default being no tolerance, and with metabolosomes and mitochondria having buffs baked into them, we have found a way to simulate this important distinction in morphology without bumping into any design problems.

Also, eventually, the difficulty in morphology shifts from becoming tolerant of oxygen to becoming tolerant of low oxygen environments, such as in the deep sea or on mountain-peaks. And, one more thing, anaerobic respiration efficiency can also become a factor.

SALINITY: As previously discussed, an important distinction in microbiology and marine science is freshwater and saltwater; and in-fact, some organisms are able to tolerate both fresh and saltwater. But honestly, I’m not sure how to represent this since there really isn’t that much intense fluctuation in salinity across the ocean. Bodies of water which are more closed off tend to be more saline, such as the Mediterranean, so maybe there’s room. Perhaps this is something to be dealt with mostly through morphology? I’ll need some help with this.

TYPE B ENZYMES (TOLERANCE, PHILICS, AND OBLIGATES)

TEMPERATURE (SCALES WITH SIZE): Mostly limited to tolerances of the polar regions and hydrothermal vents in the microbe stage, although in the future, the tropics, deserts, mountains, and arctic areas will become very consequential. Also important in that oceans near the poles are colder than oceans near the equator, so perhaps the patch map should have ocean patches with very temperatures. Temperature enzymes also scale with size, but at a rate less severe than with pressure – by late multicellular stage, the highest level of temperature enzymes should allow you resistance to most cold except the ice-caps, and most heat except hydrothermal vents. Temperature enzymes start becoming nerfed first when you reach land, and second, if you develop warm-blood. From there, features, such as sweat or fur, will also be needed alongside high-temperature resistant enzymes and anti-freeze.

Something a bit difficult to grasp with is the fact that temperature fluctuates through a planet’s geological evolution, so we’ll need a way to scale this enzyme considering that. Perhaps they are relative to the planet’s average temperature at a given time?

I’ll need help with what each level will be assigned to in terms of value, but the general thought I think is that there will be two enzymes, one correspondent with heat and another correspondent with the cold. I would think that ultimately, level 3 heat will be the only thing that matters in the cell stage to deal with the hydrothermal vents and hot springs, but the cold will have more consequences. First, the oceans trend towards cold as you approach the poles, meaning there will be certain ocean patches that could reasonably be chilly and that the frozen regions will have opportunity for higher levels of cold tolerance (chionophiles). Second, Snowball Planet events will happen.

Since level 2 and 3 of tolerances include changing the sensitivity of your organism to cold if you are upgrading heat and heat if you are upgrading cold, level 2 and 3 cold tolerance and heat resistance should not be able to be placed at the same time on the genome. Since level 1 of each upgrades don’t necessarily influence tolerance to the other however, I think they should be allowed to coexist to allow things like whales and sharks (although if you guys have better ideas as to how to allow this, let me know – metabolism can relate to this).

PRESSURE (SCALES NEGATIVELY WITH SIZE): More important for aquatic organisms, although can become relevant on land once flight and mountain ecosystems are established.

“Normal” Range – Without any adaptations, organisms will function very well on land, ocean surface areas, and shallow seas. The first layer of the open ocean under the ocean surface patches, unadapted species can manage, but begin to be impacted by auto-evo negatively. Severe drop offs begin as you proceed further.

“Barotolerant” Range – Your organism will still maintain its optimal functioning near the surface patches, but will also have a greater tolerance for the higher-placed open ocean patches and will be able to go down deeper with less impact to metabolism and auto-evo. Tolerance starts tapering off near the middle of the open ocean zone layers. Takes up 1 spot on your genome.

“Barophilic” Range – Your organism will perform very well in most open ocean zones and mid-ocean caves, but the ocean floor and its caves remain treacherous and your organism begins to lose tolerance for the surface patches. Takes up 2 spots on your genome.

“Obligate Barophile” Range – Your organism will perform very well in most open ocean zones and even the ocean floor and its caves, but will lose all tolerance for low-pressured areas like the surface patches. Takes up 3 spots on your genome.

Parts Which Help – In the microbe stage, certain membranes and their rigidity variations (more rigid is more pressure resistant and more flexible is less pressure resistance) can add pressure tolerance. Normal, double, and cellulose membranes will by default have 0 tolerance towards pressure. Chitin membranes will have a default level 1 tolerance, silicon membranes will have a default level 2 tolerance, and calcium carbonate will have a default level 3 tolerance (can be shifted depending on realism, I am unfamiliar with the differences between those three). The rigidity slider can finetune environmental tolerance ranges up to an amount correspondent to a level, allowing you more detail in defining the optimal habitats for your organism. So normal, double, and cellulose membranes can have their tolerance levels finetuned up to level 1 of resistance, chitin membranes rigidity edits can be anywhere from level 0 to level 2 tolerance, silicon anywhere from level 1 to level 3, and carbonate anywhere from level 2 to level 3. This can make membranes even more consequential, which I know has been sought out. Down the line, skeletal adjustments, armor, and other morphological features will take over, and enzymes and cell membrane type will become less consequential.

Things to Consider – First of all, to make sure I am not being stupid, would making something more rigid make it more pressure resistant, or would making something softer make it more pressure resistant? Intuitively it seems like a more solid thing is more able to deal with pressure, but I hesitate only because of blobfish – they become a lot more squishy without a high pressure environment, perhaps implying that they deal with high pressure by being a bit more squishy. The answer to this will dictate whether looseness or rigidity corresponds with heightened pressure tolerance, and I think unless absolutely bound by science, rigidity would make more intuitive sense.

Second thing to consider, should very flexible normal, double, and cellulose membranes have negative one tolerance, making it so that your species is even more sensitive to pressure? And since there is no level 4 tolerance, should there be a cool little “power” a calcium carbonate organism gets if they are as rigid as possible?

Another small thing is that the inverse of high-pressure is also a factor when it comes to mountains and flying. It isn’t really applicable now, so we can come back to that later.


With that being said, some final thoughts. Since you start off in the hydrothermal vents, you’ll obviously be in a pretty high-pressure and hot environment (I will say that hydrothermal vents vary in depth however, so perhaps in the future, the player should start hydrothermal vents which are deep but not very deep). So the player should be a level 3 thermophile and a level 2/3 barophile from the get go. This is a perfect opportunity for a tutorial. For new players, we can introduce the protein library on the first or second trip to the editor. When it’s the part of the playthrough where the player is taught how to move from patch to patch, we explain how the enzymes work – necessary since the player will be going from an extremely hot hydrothermal vent to a relatively cold ocean. We tell the player to drop their level 3 thermophile status into a level 1 chionophile status, teaching players both how to purchase a protein and interact with said protein. If this is deemed too complicated however, we can take some artistic liberties. Perhaps have the starting hydrothermal vents not be so high pressure or something.

But hey, we’ve finally reached the end. Thoughts?

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