Magicka

Basically, you and up to three other robed magician dudes go on some quest and it's funny. There's 8 different kinds of spells you can use, and you have to mix and match them for different kinds. The narrator is pretty hilarious. The game likes to poke fun of itself and its genre.

I've never really been a huge fan of fantasy games in this vein (more of a JRPG guy), but I enjoy this game. Maybe it's the humor.

Also the DLC made me laugh quite a bit:



You can pick it up on steam, gamersgate, and other places. There's a demo, too.