Hehe...I'm imagining an RTS game, where two AIs battle against each other with their massive armies...and YOU are the tiny soldiers on the battlefield in FPS view. You'd receive commands and objectives from your leader, and you, with your dozens or even hundreds of teammates would go fulfill your duty. I think that'd be a ton of fun.

The important issue in gaming isn't so much bandwidth as it is latency.  Peer to peer might work for a slower game with thousands of users like an MMORPG, but not for an FPS.

Microsoft Research made one of the best multiplayer game ever, Allegiance. I never really understood why the game was never promoted, because it was light years ahead any other. The graphics weren't the best, but the gameplay is unmatched even by today's games. It's the only game I've ever played that perfectly blended teamwork and strategy into an action game.

Allegiance was certainly a radical new gaming concept. It's unfortunate that it didn't work out better.