Non-Carbon Based Lifeforms!

That's actually pretty neat!

Obviously we would likely only find simple cells and the such there, but do you think with a few million (or billion) years, complex methane-based life could form?

Cool, although methane based lifeforms would still be carbon-based ones, as the methane replace the water( not the carbon) and is itself made of carbon and hydrogen.

About silicon-based lifeforms, I have heard that their metabolism would be really slow, even slower than the metabolism of plants.

Just so you know, it has been confirmed that Thrive will only have carbon-based life forms. But feel free to continue discussing it.

Aww, this topic was intresting and I barley knew biology. Oh well, Carbon is better than nothing anyways

Would artificial life be a thing in the game? Robots and the such?

Nice! I'm probably going to sound foolish for asking since it's probably obvious, but where can I find all of the music that has been made for Thrive so far?

Here you go:
www.youtube.com/playlist?list=PL1xZFxatUbjMxJ746nEKkvjVuNfSrQT7D

Bear in mind that in order to combust, high levels of energy are needed, so Ammonia looses a great deal of flammability at very low temperatures (correct me if I misinterpreted thermodynamics). That being said, Oxygen is very reactive regardless of most situations, so it's kind of nifty that we manage to survive with it (although the same cannot be said for 90% of life a few billion years ago). So Nitrogen would be good, especially since it could be stripped from liquid ammonia like oxygen is from water molecules in our biosphere.

Edit: I should have specified that oxygen/nitrogen is/would be stripped from its liquid for storage molecule synthesis. Inhale as needed for catabolysis.

Dinitrogen is terribly stable, though, so I don't think it could be used in the same way as oxygen is. When oxygen is stripped from water and CO2 to produce energy storage molecules, it's probably better to think of it as oxygen being the energy storage molecule, or rather, that the energy is stored by separating out molecular oxygen, and returned through aerobic respiration.

I know hydrazine is rather unstable, so maybe N-N single bonds (compared to N-H bonds, N-O, N=O, N=N, etc) could be used to carry free energy between reactants. I could see reactions moving electrons between nitrate and amide groups being used a lot, for example.

At such cold temperatures, though, I'm not sure if there would be any way to gain the amount of energy needed to fix nitrogen, so while a lot of reactions could be driven by converting nitrogen species to dinitrogen gas, it would suck if they have to rely on non-biological processes (eg, lightning) to fix nitrogen again. That puts life on a very tight timer, since any life that evolves to make use of the energy provided by producing dinitrogen would simply outcompete and starve anything that gets energy through processes with smaller Gibbs potentials, and then destroy all the available reservoirs of undigested ammonia etc, and then most likely go extinct (maybe not completely) themselves.

But if there's a reasonable chemical pathway to fixing nitrogen on a cold world, then that could be averted. It's probably possible, maybe it simply requires some interesting arrangement of metal ions, which should be more possible in an ammonia-based world since ammonia readily dissolves more metals than water. It might require a source of high-energy photons, or enough lower-energy ones to power antenna complexes like those in oxygenic photosynthesizers.