This one relies on having a graphical interface and probably needs a voxel graphics engine with 2005Spore-like body physics.
You play a person in a freshly post-apocalyptic scenario of undetermined origin where horrible mutants are roaming the streets. You are horrible underpowered and your only way to grow stronger is to feast on the flesh of the deceased mutants, to gain mutations yourself. Random parts of the corpses you eat are made parts of your body. I imagine the graphical style along the lines of Kiss Psycho Circus (but of course more varied, due to procedural generation and stuff):
The whole thing is turn-based. You can plan out your moves as far as you want, but are prompted in intervals (length depending on your stats) to correct them. The surroundings aren't rendered correctly but with random noise thrown in – distortion, omission, addition of stuff that isn't there – depending on how sane you still are (eating the corpses of mutants probably isn't that good for your sanity) and how much is going on around you (when five tentacle fiends are swarming all around you it might be a bit hard to notice what might be going on otherwise). Maybe throw in some bloodlust, causing automatic attacks on passing, which may draw aggression.
It's everyone against everyone. There should be a way to use that to your advantage, as long as you're not so insane as to make yourself autmoatically the target of everything in sight.
I imagine the surroundings being procedurally generated, with different environments like the inner city, with skyscrapers and everything, rural areas, the woods, corn fields, mine shafts, whatever.