Chicagø (abbreviated CGØ), the local branch of San Francisco-based alternate-reality game/site/creator SFZero, is hosting the Architect & the Urchin, its second-ever free street game, starting tonight at 7:30 PM at Washington Square Park (900 N. Dearborn). The rules are a bit complicated, but basically you search for 12 secrets hidden within a 1.5-mile radius of the park and collect ribbons from other players. Collecting nine secrets gets you across the "finish line" and into the Lakeview club Heart of Gold (3036 N. Lincoln, fourth floor), where awards will be given out at midnight. (Everyone else pays $5 admission.) Bring running shoes, a bottle of water, and a camera. The game will proceed rain or shine. The Heart of Gold afterparty will include a night of performance art, "As Long As The Rain Comes Down, We Will Be True," featuring a dozen works.