Space Invaders backwards, you shoot aliens into the sky who march in a pattern out into space. For all eternity.

Pacman backwards you vomit out little dots and snacks until your living space is covered with them, trying all along to avoid ghosts who are just trying to get back home.

Donkey Kong backwards you give a princess to a gorilla, then try to back down a series of beams to a safe spot at the bottom while barrels are magnetically attracted to the top, where the gorilla stacks them neatly. Eventually the gorilla gets so mad he jumps up and down to straighten out the beams, then climbs down a ladder and gives the **** back to you.