The title says it all, my roommates and I are going to face-off in a tournament. We are looking for local based games. Our systems include the xbox 360, wii, gamecube, n64, playstation 3, a pc, and ps2.

We have Halo 3, Super Mario Strikers, MW2, Mortal Kombat 9, and Super smash bros original.
We are also considering Samurai Gunn and games in that vain like the newly released Nidhogg

Any suggestions?

You HAVE to get some iteration of Bomberman. See if the Wii Store (was it called Virtual Console?) has any of the SNES titles.

Mortal Kombat 9 all the way! I wonder if we could set up forum tournaments for certain games, doesn't have to have prizes just fun and bragging rights.

You have some great games in there. If you like some sports games, those can be a hoot 4-player. NHL and FIFA especially.

I lived at "The Halo House" for a year where nearly every Friday and/or Saturday night was an epic 12-16 man Halo game-a-thon. it was spectacular.

if you haven't tried Splinter Cell: Blacklist, that has some great multiplayer team-based fun that is just unmatched, IMHO.

I'd say go for a Civ4 Tournament, but I'm not sure you are prepared for the week-long tournament. You need to purchase lots of Mt. Dew, Red Bull, Hot Pockets and Doritos.

Dude, come on! No 007 Goldeneye? That was basically the only n64 game with MP that I had aside from Smash Bros.