ok i stumbled across this little gem while browsing Xbox live arcade.
available as a demo and the full game costs 1200 ms points (quite steep but well worth it)
its basically a puzzler where you have to collect the bits of a jigsaw from each world and you can rewind time with the x button and you use this to do certain bits within the game, in one world you get to slow time down. in one puzzle theres an unreachable bit on a screen but when the jigsaw is complete it creates a shelf in order to reach the last piece.
it will have you saying `wtf` at some levels and is a real hair puller, but hey dont take my word for it go and download the demo and im convinced you will buy it after a try (unless you hate puzzlers of course)
review here...
Braid Review (Xbox 360)