Mostly demonstration games but people could join in if they wanted to. Certainly Judge Dredd and Secrets of the Third Reich were participation and ran several games throughout the day. It's always hard to get the punters to keep still for 30mins to have a play.
I sometimes think if the game looks too big and grandiose people are actually more reluctant to play "on the big stage" as it were

The smaller games like Dredd and SOTR while still looking good are less intimidating for newbies.
Cheers
Fuzzy