I'm a big fan of Bioshock, for the longest time I had 0 interest in the game but once I tried out the demo I saw that it was something special. Any game that basically casts Ayn Rand as a antagonist will pique my interest, the fact that it's gorgeous and solidly built doesn't hurt either. I didn't get around to playing the sequel though I am really interested in Bioshock: Infinite.
Playing through the initial game it was really interesting finding out more about the relationship of the Big Daddies and Little Sisters. If you want to know more go to your local library.
Some progress shots
of this piece.