The gimmick here is unusual: three cast members initiate an open-ended long-form improv based on an audience suggestion by marking up a giant blank canvas draped behind the set. Improvisers rotate in and out of the scenes in groups while the rest of the cast slinks to the side to craft new drawings, used throughout to begin or guide the scenes. Director Patrick McKenna has stumbled on a form as novel as anything since ImprovOlympic house team Georgia Pacific opted to perform entirely in the dark, but this ensemble never quite finds its balance: moments of true inspiration alternate with the usual crutches, fallback devices like goofy accents and caricatures. Meanwhile the push to churn out art on the sidelines constantly draws focus from what’s happening onstage. Through 10/8: Fri 8 PM. Second City Training Center, Donny’s Skybox Studio, Piper’s Alley, 1608 N. Wells (fourth floor), 312-337-3992 or 877-778-4707. $10.