At the 'Game Selection' screen press Up, Up, Up, Down, Down, Down, Left, Right, Left, Right, Left and then start either game.
Play Demo for Free:
Watch the Galaga demo and when a spaceship comes down and tries to capture you repeatedly press Fire to destroy it. Move the Joystick and you will move in the direction that is pressed. When you hear the sound of Pac-Man dying a message will appear on screen saying that all ROM is OK and the game will then proceed with the Ms. Pac-Man demo.
Added by: Sanzano Sep 14th 2007, ID#190