Just beat Tower of Heaven. It's a really cool indie game that looks like Cave Story for Gameboy. Basically, you're this blobby guy who needs to climb a tower to stop God from making too many rules. As you progress, God makes more rules, like "Don't touch the sides of blocks" or "Don't walk right", and the levels get pretty clever. Doesn't take more than an hour to beat, if that.
http://www.askiisoft.com/download.php?id=1