Both Hands at Once

A row of hand shapes for your left hand and a different row for your right, read left to right at the same speed. The shapes are easy — a fist, an open hand, one finger — and the game is not, because your two hands are not two independent machines. It is pat your head and rub your tummy, written down. Nobody marks it: you feel the mistake the moment it happens. Print it again with a new seed for a row nobody has ever done, and turn the difficulty up by adding shapes.