Robo the robot has fallen to pieces. He calls out a move, like "10 jumping jacks!" or "reach for the sky!", and the camera counts as you do it. Every finished move gives Robo a new part: legs, body, arms, head, eyes and antenna. Build the whole robot to make him dance, then build another one.
Little players get fewer reps and hear their count out loud. Big players get more reps. Robo waits for both players to finish before he gets his next part, so cheer each other on.
Put the laptop on a table, turn the lights on, and stand about three big steps back so the camera sees you from head to feet, side by side. The camera picture stays on this computer and is never sent anywhere.