I know of a Cthulhu Live! group that were contemplating something like this, a few years ago - but it was based off the CIA experiments with psychoactive drugs on unwitting subjects. There was much discussion about how to hide projectors and speakers and such in order to simulate hallucinations for the players, without clueing them in ahead of time, and if it would be safe to do a 48-hour always-game-on event, in which one group of players completely controlled the environment of the other, etc.

I don't know if the game ever happened, but I almost hope it *didn't* as it did sound a bit... much...