For the first time in about a month I played a game more than once in a day. And that game is Tomb Raider Underworld. Seriously, that game has me in its' claws. The puzzles are quite interesting, kind of like Prince of Persia: Sands of Time since there aren't a lot of them, but they're big and central to the gameplay. I'm really liking, especially for $40.
Although, it's not without its' flaws. It's kinda touchy with some of its' gameplay, and the camera is bad in some places, but very rarely will it result in you dying.