On the title screen enter; 1P, Jump, Bubble, Left, Right, Jump, 1P, Right

At the title screen enter: fire, jump, fire, jump, fire, jump, right, start(2p side)

Get to level 50 without dying.

Finish a level with 98% of the playing surface covered.

Get all the way to Level 20 without dying, and a door will appear on the screen. Enter the door and you'll be taken to a secret tomb, which is a level full of diamonds.

If the alien at the bottom-left is the last one killed, your bonus will increase to 1,000 points.