Mutant Dreams: Reactive Mutations In Shrooms
I never asked for this

Had I chosen my own mutations, I probably wouldn't have gone with astigmatism, Raynaud's phenomenon, and a leaning towards alcoholism. Them's the breaks, though. Roll with it. I wish more games took this tack, giving you attributes you didn't ask for, builds that can't be honed and optimised, only dealt with. Roll with the punches and see where the journey takes you, man.
Shrooms [official site] talks big talk of mutations and evolution driven by infections, morphing your body to suit what happens to you rather than following your whims. I, obviously, dig that idea.
"In the world of Shrooms, your body will get infected and start mutating according to what you eat, where you live, what attacks you, etc." explains a recent dev update. Lovely. Splendid. That sentence sounds fab and I would like to see that idea in a game.
Unfortunately, Shrooms puts all this in a multiplayer crafty-explore-a-survive-a-sandbox - a genre that simply isn't my bag. It does sound like they're aiming slightly beyond being Just Another One Of Those Games, mind. Plans include co-op crafting, like one player holding a sword while another wails on it with a hammer, PvE raids, and changing weather.
But back to unchosen attributes. Rogue Legacy had some fine mutations, both good and bad, giving you characters who might be dyslexic, monstrously strong, giant, a bit farty, and so on. I always liked the idea of combat scars in Fable games, but one could remove them. Rather than list examples myself, I'll turn it over to you: what else, gang?
Me, I'm more fascinated by the idea of reactive, unchosen mutations than Shrooms itself, but here's a glimpse at an early version if you are curious: