Introversion, best known for their strange game Darwinia, has announced its next project, Prison Architect. As the game implies, your job is to build, maintain and run a maximum security prison.
Nothing else is known about the game, but the possibilities for this kind of game are surprisingly deep, since part of prison building involves being able to monitor hundreds of inmates with as few personnel as possible, as well as keeping prisoners from starting brawls in the cafeteria or open riots. The game will also have to deal with making sure model prisoners stay alive and healthy, while more violent prisoners are punished properly.
Introversion promises more info on this title - it'll be interesting to see what kind of game they've come up with.