Suffer mode:
Enter "ICHEAT" as a name. Then while playing a game, press C-Down, Up, Z(2), C-Right(2). Repeat the code to disable it

Dancer:
Enter "ICHEAT" as a name. Then while playing a game, press Down, Up, C-Up, Down, C-Right, C-Right.

Smart Bomb:
Enter your name as ICHEAT, during the game press A, C-Up, C-Up, Up+Left to launch a smart bomb. The bomb will destroy all minor enemies, shield generators and processors on the screen.

All weapons:
Enter ICHEAT as a name. Then, press A, Right, C-Down, C-Right, C-Up, A, Left during game play.

Weapons power-up:
Enter ICHEAT as a name. Then, press Down, Up(2), Z(2), Left, Right during game play.

Surreal graphics:
Enter ICHEAT as a name. Then, press Down, Up, Right(3), A, Left during game play.

All artifacts:
Enter "ICHEAT" as a name. Then while playing a game, press Up, C-Down, C-Right, Z, Up, Left.

Weak Boss:
Enter "ICHEAT" as a name. Then while playing a game, press Z, C-Right, C-Right, B, Left, C-Right.

Mutant alien:
Enter ICHEAT as a name. Then, press C-Down, Up, Z(2), C-Right, Right during game play. Enabling this cheat while facing a harvester will transform turn that alien into a mutant.

Fat legged aliens:
Enter ICHEAT as a name. Then, press Left, A, Right, Down during game play.

Restore health and fuel:
Enter "ICHEAT" as a name. Then while playing a game, press Down, Up, Right, A, B, Left, C-Right

Tall Adam:
Enter "ICHEAT" as a name. Then while playing a game, press B, A, C-Up, A, C-Up, A.

Short Adam:
Enter "ICHEAT" as a name. Then while playing a game, press Down, C-Left, A, Right, Z.

Kill Adam:
Enter "ICHEAT" as a name. Then while playing a game, press B, Left, C-Right, C-Right, Down.

Black Adam:
Enter "ICHEAT" as a name. Then while playing a game, press C-Left, C-Right, A, C-Down, C-Right, Left

Additional difficulty levels:
Repeated press Left at the difficulty selection screen to access the "Very Easy" setting or repeatedly press Right to access the "Very Hard" setting.