Prehaps a crature evolution one? yknow, youre a samll animal, and try to survive in a big world, and as times passes (and you gain XP) you evolve and have better weps, etc.
Long ago I had one, however at that time I was way busier, so I passed it down to a player who liked it a lot, after that I dunno how it went, it was called Evolve! (i think), you were a small cell (think of Spore), the game master added a story as to what was happening, and the player chose what to do.
well, thats the main kind of evolution game, so its much more likely you´ll see baby raptors n such, instead of cells evolving, also, almost all of these games have the GM adding story, and players answering from 4 diferrent answers (even tho 1 of them normally says "explain your action/movement/etc)