I’d like to expand this topic to discuss reproduction systems more broadly. (If that’s hijacking your topic, Deus, I’m sorry and this can be moved to a new topic. I chose this topic mostly based on the title)
There’s been a lot of discussion about sessile organisms and reproduction recently, which is good to see in my opinion. I’m going to first describe the current reproduction system with its pros and cons, then talk about what goals a good reproduction system should fulfil in my opinion, and then list and evaluate some potential new reproduction systems. This’ll be focused on the microbe stage but could be useful for future stages too. I’ll use the word “sessile”, but “non-motile” could be more accurate sometimes. “Growth rate” will refer to how fast you grow, and “reproduction time” to how long it takes between birth and reproduction.
So how’s the reproduction system currently? It’s pretty simple: You collect enough ammonia and phosphates to divide your organelles and then click a button to reproduce. You get ammonia and phosphates from compound clouds or other cells. This works great for the average cell that’s of medium size and decent mobility. It usually isn’t too slow or too fast. It’s active, easy to learn, pretty fun and teaches something about real biology. Sometimes however, it’s a different story. You can get lucky with spawns or store nutrients from the previous patch and reproduce so fast that you barely see the patch, effectively skipping it and its challenges. On the other side of the spectrum, you have cells that are slow, big, or unlucky and can take dozens of times longer to reproduce. And then sessile autotrophs can’t reproduce at all. All this even though big, slow and sessile cells all exist on Earth perfectly fine. This feels unnecessarily limiting, punishing and boring. Simply put, reproduction takes too long for some organisms and too little for others.
To better understand the issue, let’s take a step deeper. What is the purpose of reproduction and the time it takes in the game? Personally, I think it’s to both show the full life cycle of the player species (or at least its most important parts) and to give the player an interesting challenge: to prove that their species really is viable. How much should it be like real life? For example, should a whale like creature take dozens of times longer to reproduce than a mouse like creature? Probably not, as that doesn’t sound very fun. Time is very abstract in games and I don’t think that this abstraction really hurts scientific realism. I think that many different kinds of reproduction systems fit under a simplified, abstracted reality, so we can pretty freely focus on what’s best from a gameplay perspective. In real life, growth requires time, energy, and nutrients, but for gameplay reasons we may choose any of them and abstract away the rest, like how the game already does. If we still want bigger organisms to take longer to reproduce for scientific reasons, that’s fine, but only so long as it doesn’t hurt gameplay. So the difference in reproduction time should probably be relatively small. With the purpose in mind, what makes a potential reproduction system good?
Goals for a good reproduction system
- All organisms should reproduce in a reasonable amount of time. This means that you can’t reproduce so fast that you skip on the challenge, nor so slow that it gets too boring. Reproduction time should probably be pretty consistent across different kinds of organisms too keep different strategies interesting. So big, sessile and/or autotrophic organisms should take a pretty similar amount of time to reproduce as small, motile and/or heterotrophic ones. Otherwise the game would be punishing those strategies with boredom. I think it’s much more effective and fun to “punish” bad strategies with poorer ability to get enough energy to survive.
- The player should have some agency in their reproduction time. Agency feels good and fun, having no control feels bad or boring. Agency lets players play in their own style. New or casual players can take the scenic route where as experienced players and speedrunners can try to go as fast as possible. Without agency the game can easily become a waiting simulator if survival isn’t challenging enough.
- It should aim to be scientifically realistic without sacrificing fun, like everything in Thrive. It’s fine to simplify things for the sake of gameplay or ease of learning. Straight up inaccurate things like phosphate generating organelles are a big no-no.
- It should be intuitive and easy to learn. New Thrive players are confused enough as is.
- It should be feasible to implement. Everyone wants the microbe stage to be “finished” at some point. If a new system is going to require redoing a lot of code, testing and balancing, then it’s going to require good justification as well. We don’t want to burden the developers with unnecessary work.
Concepts for possible reproduction systems (in no particular order):
Wait for currents
Change nothing about the current system and just wait until water currents are implemented. They’d make sessile cells capable of reproduction by making them hit nutrient clouds sooner or (more likely) later. It’d basically be like random, slow movement for them. Currents would also make the world more fun and visually interesting for all cells. However, many cells would still take a very long time to reproduce, especially in patches with slower currents. That’s why I don’t think that this is a sufficient solution.
Passive absorption
Do what Thim did in his fork or what the devs are discussing in Revamping Compound Clouds. Make cells passively absorb ammonia and phosphates. The absorption rate could be affected by membrane type, surface area, patch, etc. This would give all cells a consistent maximum time for reproduction while leaving motile cells the option to pursue nutrients to grow faster. This is a pretty simple change that solves a lot of problems without breaking old stuff too much. It’s also easily modifiable with just a couple of tweakable constants needed. I think that this is a great idea to test first and collect some feedback. Does it affect player behavior or fun for normal cells and if so, in what way? Does it make sessile enthusiasts happy? What kind of absorption rates are good? Is it intuitive or confusing to have both passive absorption and compound clouds? So many questions, I’m curious!
Time-based growth
This is pretty similar to the previous one but more ambitious. Each species would have a specific reproduction time based on its morphology. Ammonia and phosphates would just boost the growth rate or have other uses. You can read more from Deus’s previous posts in this topic. This would put the focus on survival instead of collecting ammonia and phosphates. This is a bigger change and would require a lot of thought and testing. It would make reproduction nicely consistent. On the other hand, it could end up as a waiting simulator if surviving is too easy or growing takes too long, but that could be diminished with balancing. Personally I think that size shouldn’t have much impact on reproduction time because it affects fun a lot.
Time-based growth could make ammonia and phosphates feel a bit useless sometimes. If that’s the case, I’d suggest making both ammonia and phosphates boost growth rate, healing, and toxin production (and maybe even more things). If you had both, the boosts would be added together. Alternatively, you could straight up get rid of ammonia and phosphates and boost growth with energy. If you find a big chunk of food, you should probably be able to reproduce pretty quickly rather than having to wait with a full storage (although defending that food pile from competitors could be interesting). Maybe a button boosts growth at the cost of ATP or excess food goes straight to growth. Overall, I think this could have potential with some tweaking, but it’s hard to tell yet.
Food-based growth
We could abstract away the nutrients and focus on energy from food. Many games make animals grow instantaneously by eating food. It’s active, simple, pretty fun and keeps focus on something that’s necessary for survival. This is more complicated in Thrive however, because not every organism is a normal animal. I guess plants could consider the glucose they make food, making them grow at a consistent rate as they produce more of it. Heterotrophs would grow whenever they eat other cells. But what about a heterotroph that has a single rusticyanin? Should it grow just as well from eating iron? Probably not.
Maybe the instant growth is calculated based on how many metabolizing organelles you have. Maybe growth could happen at the rate you metabolize the food for energy, but that could increase waiting again. Or maybe you need glucose to grow. But that would hinder iron eaters unless you can synthesize glucose with energy from inorganic compounds like CO2, in which case glucose is kind of an unnecessary middleman. I think that this is a harder system to figure out, but if it were to work out, it could make sessile organisms viable without risking a waiting simulator for motile cells.
Static ATP consumption
Constantly consume ATP to grow. You could tweak the rate of growth in the microbe editor, within some reasonable minimum and maximum values. Big cells could grow at a similar rate to small cells since they have more ATP to spend. Autotrophs could sacrifice movement to grow faster. This system is essentially passive growth, so perhaps active cells could have a button that makes them grow faster at the cost of more ATP, that way they could choose their growth rate based on how much food they find and get back some agency. Passive growth makes ammonia and phosphates unnecessary, so they could either boost growth, have some other purpose or be removed.
This system would work pretty similarly to passive absorption and time-based growth, just putting the focus more on energy rather than nutrients. It does give a nice freedom to choose your rate of growth, but it could perhaps be awkward for new players to think about how much ATP they spend on growth. I guess they could just ignore it if the default rate of ATP to growth goes up as you add organelles to your cell. This could work, it’s mostly a matter of which things the reproduction system wants to focus on.
Dynamic ATP consumption
Grow based on how fast you consume ATP during gameplay. If you move, you grow faster. If you make toxins, you grow faster. If you have a higher osmoregulation cost, you grow faster. This makes growth automatically scale with size. This also makes it so you never have a reason sit still once you have enough food to grow until reproduction, since that would just slow you down and it wouldn’t affect how much food you need to reproduce. This gives players who want to go fast the interesting challenge of maximizing how much energy they gain and consume. However, species with little energy would grow slower, which could be unfun for them. Also, it may be weird that moving speeds up your growth. This would also make ammonia and phosphates useless. I don’t know if this idea makes sense, I just found it interesting.
Remove phosphates from the game
We could just abstract phosphates away from the game by assuming that the player passively absorbs enough of them. This would actually make gameplay very similar to the Phosphate Generation mod. If you’re a normal cell, you can play the exact same, just worry about one less compound. If you need help with growing, you can add nitrogen fixing organelles to your cell. This would be a bold but simple change. It’d certainly work, but it does have its flaws. It would mean that all sessile cells would need nitrogen fixing organelles. New players would probably miss those organelles and wonder why they can’t reproduce. We wouldn’t have the chance to teach about phosphates being essential for growth. There would be less diversity in needed compounds (this is both a pro and a con). I wouldn’t personally go with this one.
TL;DR: Sessile, slow and big cells struggle to get phosphates. Surviving from birth to reproduction should be an interesting challenge. Reproduction time shouldn’t be too long or too short. We could try new systems like passive absorption. We should be wary of breaking the game loop, confusing new players or causing too much work for the devs. We can diminish the risk of a waiting simulator with challenging survival, more ambiance and player agency in their rate of growth. All things considered, I think a new system is a good idea, maybe even a necessary one.
Now that’s probably enough for a conversation starter. If you didn’t guess, I’m pretty passionate about this stuff. It’s one of the reasons I got into messing around with Thrive’s code and made the Phosphate Generation mod. I hope that one day life in Thrive will be as diverse as possible. Biodiversity makes for interesting alien environments and gives players more creative freedom and strategic options. Ideally all viable life forms would be fun to play as at least for some people. I think that with all this is mind, a new reproduction system is necessary sooner or later. I don’t know which system is best, which is why I made this post. I want to encourage people to think about this stuff and share their thoughts. I think that it’s a good idea to start trying to figure this stuff out sooner rather than later, because changing reproduction could affect the whole game. For example, if sessile cells could reproduce, then the developers would be freer to add things that encourage or require slowness or sessility, like tankier cell walls. That could change the whole balance of the game. If we leave reproduction changes until later, there may not be much time to do them before 1.0, or plenty of things could end up having to be reworked.
Of course, it could be that none of these proposed reproduction systems make the game better, and some of them could be too much work even if they did. I’m not demanding anything from the busy developers. I just think that there’s a lot of real potential and that it’s a worthwhile idea to test some simple options. When it comes to some of the wilder ideas, I may make some kind of prototypes for them myself one day if they seem promising enough, but that would be still long ways of, and it may well be that the simplest ideas turn out to be the best ones.
I think that testing out simple passive absorption in practice is a good start. If you can, please add the rate of absorption as a tweakable constant in new game settings. That way players can experiment with different values and offer lot of feedback quickly.
If anyone has any thoughts, please share them! Also if anyone has feedback on how reproduction feels with the phosphate mod or Thim’s fork, that would be great to hear as well!
