If you're never played the game Portal, you're really missing out. It's a crazy game that … I don't even know how to explain it. The object is to get from room to room and your only weapon is a little gun that zap you around. Okay, that makes it sound stupid, but trust me when I say it's one of the better puzzle games out there.
Making it even better is that from now until May 24, you can download it onto your PC or Mac for free via Steam. The download is fairly large, so you might want to start it before you go to bed.