Full health:
Pause game play and press A, C(2), A, B(2), A, C, Start. The word "cheater" will be spoken to confirm correct code entry. Note: This code may only be used once per level.

Level skip:
Pause game play and press A, B(2), A, A + C, A + B, A + B, A + C.

Level select:
Pause game play and press Left + A, B(2), A, Right + A, B(2), A.

Power-up:
Pause game play and press A, B(3), C, A, C(2). The word "cheater" will be spoken to confirm correct code entry.

Extra continue:
Pause game play and press A, Left + B, A, B, A, B, C, A. The word "cheater" will be spoken to confirm correct code entry.

Extra life:
Pause game play and press Up + B, B, A, C, A(4). The word "cheater" will be spoken to confirm correct code entry. Alternately, pause game play and press B(2), C(2), A(4). Note: The alternate code can be enabled only once per level.

Debug mode:
Pause game play and press Left + A, B(2), A, Right + A, B(2), A. A picture of the development team will be displayed to confirm correct code entry.

Nine plasma guns:
Pause game play and press Down + C, A, B, C, A, B, A, C.

Nine homing missiles:
Pause game play and press Right + A, A(2), B, A, C, B, A.

1000 rounds of ammunition:
Pause game play and press A, B(3), C, A, C(2).

Jump to the "What the Heck" level:
Pause game play and press Left, Right, A, B, C, Left, Right, A, Start.

Jump to last level:
Pause game play and press A + C, A + B, C(2), B(2), A(2).