Über

One housemate is playing both sides. The Menace gets chores too, but only as cover. Their real job is wrecking yours: snatching items out of your hands, jamming doors shut, cutting the lights, then drifting back to the dishes like nothing happened. After each round the whole house votes in secret on who they think it is, and nobody sees the results until the match is over. The twist is that sabotage covers the Menace's tracks. Every job they pull off quietly wipes suspicion off their name, so a sloppy Menace gets caught while a careful one walks free. If the votes still stick, the hardest-working housemate wins. If they don't, you all just lost to someone who spent three rounds doing the washing up.