That's a great idea. I don't think I've seen a model fairground used in gaming before, but with the big tent as a centerpiece, this could be a lot of fun.

Arabin

If you could set it up with the big top being in the middle you could sort of funnel players to the middle through an ever increasing set of dangerous situations. Using a lot of beat up fencing the entire set up could take on an almost maze like quality.
To throw a curve into it, just think of putting the whole thing on a pier, sort of like Coney Island. I'd be real interested to see what someone could come up with for a hall of mirrors, house of horror, side show, and eventually the aformentioned big top.

Hmmm. Yes, with PT Barnum's "The Great Egress" door, a fancy name for exit, which folks paid an extra coin to just go out the exit. This could be placed on the end of the afore-mentioned pier. Or over any number of traps. Good for those monster clowns and other fun stuff. Use transparencies over printed matter to make the house of mirrors. Oooh, I see lots of possibilities. A dual purpose set, maybe, with monster and "normal" circuis potential.

Tom

It would definitely mesh in with the Horror Genre.

Ooh, Ooh! Mini-game title: Big Top of...DEATH!

Animal cages...definitely need animal cages.

Big Top of...DEATH!
BRILLIANT!

This definitely gets my vote!