I was just thinking that it would be really neat (people still say neat, right?) if you could modify your character's genetic code. For instance, on a world without oxygen or with low oxygen levels where a respirator or space suit would normally be needed your character would be able to breathe easily. The process would be difficult but you could avoid the movement buffs that I'm sure would come with a bulky spacesuit. The modifications could be physical, too. Run faster, take more damage after armor effects, etc. I also think genetic modification would make more sense than, say, heart crystals in Terraria. I understand this isn't the same game at all, but that's the only comparison I could draw.
