If you have an Xbox-360 and you haven't tried out Braid, you're missing a very fun game. Get on Xbox Live Arcade and at least try out the free trial, and then go buy the game.
Braid (by Jonathan Blow) is a platform-based puzzle game (with many throwbacks to the original Super Mario game) that uses various methods of controlling time to solve puzzles. It challenges how you think about time by providing a different mechanic throughout each of five levels. The gameplay is unique, the music is captivating and the art is vibrant and rich. The end of the game is mind-blowing (I'll admit that I didn't "get it" the first time I played through the last level).
I can't say enough great things about this awesome game. Go check it out for yourself.