I used to play airsoft a few years ago. The main problem with that would be the relatively large expense to start playing, and the need for a very large area. I agree that there should be more than two teams, as I've said elsewhere, and the lack of respawns would make sense.

Possibly, however, limited-range weaponry would be more fun/useful/easy to deal with - nerf/boffer swords, (which I admit I have no experience with) thrown weaponry, like tennis balls or dodgeballs, and so on.