RimWorld is a game built on an interesting premise: the official website describes it as a "sci-fi colony sim driven by an intelligent AI storyteller. . . . It's not about winning and losing - it's about the drama, tragedy, and comedy that goes on in your colony." You choose from a few preset options that will affect the degree of in game events, but apart from that, your story will vary each time.
You are responsible for managing your colonists, who are survivors from a crash and who all have different skills and needs. You and your colonists will have to deal with things like disease, pirate raids, and weather, among several other individual traits of your colonists.
No official Steam release date, but you can pre-order and find out more about the game at rimworldgame.com.