It was brought up that explaining the game would be a bit difficult. I don't think FIRST is about any specific game, so why constrain the idea to any year's game? Have a simpler field, simpler goal maybe? Or maybe it's a balloon instead - a gigantic FIRST logo
Either way, here's another idea (or a wrench in the gears): What if it was interactive? The floats stop at times - pick up a few drivers and/or players - let them drive and play the game. Again, it'd have to be simple. And of course everyone is going to scream "you can't do it...to dangerous." I think if the game is simpler and the right precautions are taken, it's feasible, although still a crazy idea. But imagine if they got those boring (IMHO) announcers off that stand and down on the float to play a round or two