disregard these boring things, here's a good idea. invite peeps into the party, then use some sort of thing to ask them to play hide and seek. then, players get their map and name things removed so they can camouflage in the bushes. cool eh?
it's probably been said already. never mind. also, some other party games, i don't know what you all play in america.
edit: some other ideas:
sprinting = you know, rapidly press two buttons until you reach the goal?
moving log on the water = because it sounds cool
dance = pressing the buttons like in other generic games.. like guitar hero... :/