Unlimited bombs:
Pause game play and press I, II, Left, I, II, Up, I, Down, I, II, Select, Up, Down.

Unlimited ammunition:
Pause game play and press II, Left, II, Up, I, Right, I.

Nine credits:
Enter sound test option and play the following songs (in order): 0, 3, 3, 8, 3, 9, 0, 0, 8, 0.

Unlimited credits:
Enter sound test option and play the following songs (in order): 3, 4, 3, 8, 0, 1, 4, 1, 14, 14.

Maximum HP:
Enter sound test option and play the following songs (in order): 3, 7, 3, 5, 1, 8, 2, 1, 9, 8, 4.

Arcade mode:
Enter sound test option and play the following songs (in order): 7, 7, 7, 7, 9, 3, 10.

Start at second half of game:
Enter sound test option and play the following songs (in order): 1, 6, 0, 10, 5, 2, 10, 3, 8. Game play will begin after powering up with heavy artillery and speed.

Fast mode:
Enter sound test option and play the following songs (in order): 7, 5, 8, 4, 1, 10, 5, 1, 10, 5, 1, 8.

Slow mode:
Enter sound test option and play the following songs (in order): 0, 0, 0, 0, 0.