Speculative Preenactment. Like the SCA or Civil War players, only for the future. Not like a LARP, with stats and storyline and such.
This came out of a bit of discussion of Uru as an Alternate Reality Game, rather than a MMORPG. Blade actually participated in Majestic for a while, and I would count The Stone as a puzzle based ARG, because of its offline comunity aspects.