SSB would be a great game for a party. In my experience, FPS games are usually too competitive for a party. Smash Brothers however, is a different story. One or two consoles set up would be fun. Heck, set it up with any watchable multiplayer game and you'll get people cheering and having fun.
I'm more partial to the team vs team dodgeball game though. If possible, depending on the size fo the teams, have the robots playing in it too. Though they better have bumpers. That said, I hope we can take off the speed blocks on the muzzle velocity in the code first
Frankly, just a general place to hold that many people would be great. Most of all, food, drinks, speakers (the music will show up, guaranteed), and nice comfy chairs. Oh, and cameras. Can't forget those, can we?