Not only is it an awesome game, it can be a true art. I have seen four-square players who turned the game into a noncompetetive sport, similar to hackeysack, which allowed them to pull tricks you'd never imagine.
Ever seen someone do a flip after deflecting a four-square ball, land in a push up position, and then deflect it again with their head? I'm telling you, these guys were amazing.
Yeah, there are also games at the University of Pittsburgh. I never played because I was convinced it was a secret front for the bible study group run by the founders of the club. Recently, I mentioned this to one of the current officers of the Pitt foursquare club and she mentioned that the founders really were into their bible study, but they ran foursquare separately. I missed out.
I am ashamed to admit this, but I played that all the way through 8th grade.
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Now that I know what Foursquare is, I have to say, foursquare seems preferable.