During intro screen press 'Ctrl', 'Esc', 'F2', '5', 'V', 'J', 'Right Alt', 'Help', 'Left bracket' & 'Enter' on numeric pad (may require a friend to help press all the keys together). Now when the title screen plays, the bottom of the screen will flash to indicate that the cheat is activated. During play the 'Help' keys skips levels. The 'Q' key turns off the collision detection, and the '1' and '2' keys give more energy for player 1 and player 2, respectively.

When you reach the continue option screen and, if after the word credit, it says "1", start tapping the '1' and '2' keys alternately, all the way through the change disk prompt until both men fall from the sky. This gives you infinite lives.