Over the past few years I've made a habit of bemoaning the atrophied state of Chicago's performance-art scene. Two decades ago it was difficult to avoid challenging, enigmatic, convention-defying work in galleries and clubs around town, but by the mid-1990s all the venues had closed. Yet one well of courage and creativity never ran dry: Goat Island. Since debuting in the mid-80s, it has carried the banner for intricate, task-based performance work, and in the process it has inspired a welcome new generation of performance-art troupes--first Lucky Pierre and now the bold and ridiculous Cupola Bobber. This two-man company takes the Goat's repetitive, quotidian chores and streamlines them, finding their essence. In their debut piece, Subterfuge, Stephen Fiehn and Tyler B. Myers spend two bumbling hours together in a makeshift forest of 36 two-by-fours standing on end. With childlike inefficiency, they try to construct some sort of comfortable existence from the few odds and ends they've given themselves: a leaf, a cardboard box, a balloon or two. But in their clownish incompetence, they completely level their forest--the only beautiful thing in their world--and then transform it into a towering, useless monument. With its poker-faced tedium, Subterfuge is as playful as it is demanding, and Fiehn and Myers, both only 23, show enormous maturity in trusting the simplicity of their vision. Spareroom, 2416 W. North, 773-645-8075. July 20 and 21: Friday-Saturday, 8 PM. $5.