Here are 3 easy cheats you can do.

1. On the menu screen, press 1, 2 or 3 to go to level 10, 20 and 30.

2. When you beat level 6, shoot the blue then green target to get an extra point and life.

3. When you beat level 10 wait 30 seconds and a blue ship will appear, shoot it to go to secret levels!