Think you know San Francisco? Well, the folks at the Go Game think there's a side to our beloved city you haven't discovered yet -- and they've devised an urban adventure game to prove it. Described as a "scavenger hunt meets Mission: Impossible," the Go Game leads teams of players to well-known and obscure parts of the city, where they are asked to think through a brain teaser, find a little-known piece of San Francisco history at a city monument, or film a music video on Mission Street dressed as Britney Spears. Through these "missions" (30 of them!), fed to you via cell phone through the wireless Web, the Go Game will direct you to find places you never knew existed, see things you never noticed before, and do things you never thought you'd have the guts to in public. Are you up for the challenge?