Braid

Braid is a Mario like puzzle paltformer that I heard about on kotaku first, I downloaded the free trial version and man was I hooked right away. Its creator Jonathon Blow admits Mario's influence and there are many hints in the game that show the Nintendo love in general. I have not been impressed with a puzzle game like this since Portal.

If my word is not enough then checkout the Joystiq Meta Review which is basically 4 reviews in one. 1up guys gave it an A+, which if I'm not wrong is the highest possible. The Eurogamer guy summed it up best:

"I've gone to bed thinking about Braid, and I've woken up thinking about it. From the fragments I remember, I'm pretty sure I've dreamed about it as well. Braid is that sort of game."

If you like puzzle solving games you have GOT to check it out. Hey, the trial version is free!