A party I went to had a game called kiss carry cuddle. You play music and have someone with their back to a dancing crowd, in this case, parent child pairs. Music stops, everyone adopts one of three poses. Back turned person calls out kiss carry or cuddle. Those in wrong pose are out. Repeat until winner. You would have to modify the three poses, but it could work for any size crowd, takes no setting up, is unambiguous, and won't send little kids totally mental. Only issue I could see would be cheating. Another more hectic game was to have a giant dice and six numbers around the room. When the music stops, you go to a number. The giant dice is rolled, everyone at that number gets a token. Person with the most tokens after a certain time wins. I've only seen them with groups of about thirty, but I can't see why they wouldn't scale up.