I’m not dismissive of these ideas regarding photosynthesis. Realism is fun, but there should also be some leeway for being innovative i.e. create speculative evolution. It should also not be too loose and easy, because everything comes at a price, but I can see your challenges. I need to sink my teeth into the subject more to come with something more qualified, but here are a few things from the top of my head:
- I’m actually a bit puzzled as to why light is expressed in percentages and not e.g. absolute units like lux or watt. Also, 200% lux makes no sense to me, because percentages over 100% indicate growth. So, I suggest we first of all go over to absolute values.
- Using absolute values, it actually becomes interesting, because then you can vary light levels depending on not only depth, but also day/night cycles, as suggested. Sunny spots would be fine, but it would make even more sense with e.g. clouds or cloudy days.
- Another thought I had, already mentioned by Nokk, I see, is capping. Simply put a cap to the amount of energy (ATP) that can be harvested from certain light levels. In other words: Even if there’s more than plenty of light, you won’t get more energy out of it, due to physical constraints that are imposed on photosynthesis.
- I’m not sure overheating is an actual problem IRL for photosynthesizers, but I could be wrong.
- Also I never heard of chloroplasts adding too much weight, but again: I could have missed that information.
- At different depths, different spectra of light dominate, which is why e.g. red algae dominate at lower depths, and green algae in the highest levels. Maybe also something to take along. If you want to thrive in lower light levels, you need different kinds of pigments.
- Something even more fun and competitive is shading. Now the current gameplay appears to be top-down, but we could impose it to be sideways, meaning the top half of the screen is above. And that means that cells at that level block light to some degree, making it an advantage to struggle to get to the higher levels. This is also akin land plants growing to get the most light, while those left in the shadows have fewer resources.
- Now that I’m at it: I had another idea, as sessile species haven’t really been considered, because that seems boring. However, species that can stack their static cells into growth forms that branch out throughout the water could provide interesting gameplay for even non-swimming species. This remind me a bit of several mobile apps like “Tentacle Wars” and “Auralux”.
- For benthic zones, we could even provide solid growth substrates, i.e. rocks and sand for sessile species to grow and expand from.
OK, those are some pretty wild ideas already, so let me know what you think.
EDIT: I just realized I opened the door for “Microbial Mats”! 