It's over for the year, but see if there's a local Global Game Jam competition near you for next year.

http://globalgamejam.org/

It's an Iron Chef style challenge where you're given a theme and a couple days to make a game with a group of people. I've done it twice, and it's both a load of fun and a great way to meet people. While it's not an art/design specific contest, you'll be able to work on a team as an artist/designer.