Great video game where you have to use a paddle shaped thing to bounce a ball around an arena, knocking out bricks and getting all sorts of spiffy power-ups that make your paddle bigger, smaller, causes the balls to reproduce, gives you trillions of balls, etc. Has a great sequel, Arkanoid II. This game was ported to just about every platform in existence; so far I've only played the Apple IIgs version.

The game has an amusing story to it concerning spaceships and an evil being determined to rule the world, but that's just icing; this is really Atari's Breakout on steroids.