I just had my mind blown by the trial of Braid, by Jonathan Blow, which just came out on XBox Live Arcade. This is the most interesting puzzle game I have played in many years. It’s a platformer about playing with time, and in incorporates this very effectively to allow clever solutions to puzzles which seem impossible. Not very many games get my money these days, but this one does!
Bravo!
Make sure to beat it, the ending is totally worth it.