Cheat mode
Fire and reload the lightgun or controller at a blank portion of the main menu to spell out the code words. The number of times Fire is pressed corresponds to a letter in the alphabet, with 1 being the equivalent of "A" through 26 being the equivalent of "Z". Press Reload to move on to the next letter. .
Master code
Enter "MEBIGCHEAT" as a code. Press Fire(13), Reload, Fire(5), Reload, Fire(2), Reload, Fire(9), Reload, Fire(7), Reload, Fire(3), Reload, Fire(8), Reload, Fire(5), Reload, Fire, Reload, Fire(20), Reload at the main menu. The screen will flash to confirm correct code entry
Arcade mode
Enter "BLAM" as a code. Press Fire(2), Reload, Fire(12), Reload, Fire, Reload, Fire(13), Reload at the main menu. The screen will flash to confirm correct code entry The "Arcade Mode" option will now be unlocked in the extras menu. Alternately, successfully complete the game.
Country challenges
Enter "ABROAD" as a code. Press Fire, Reload, Fire(2), Reload, Fire(18), Reload, Fire(15), Reload, Fire, Reload, Fire(4), Reload at the main menu.
Mighty Joe Jupiter mini-games
Enter "MIGHTIER" as a code. Press Fire(13), Reload, Fire(9), Reload, Fire(7), Reload, Fire(8), Reload, Fire(20), Reload, Fire(9), Reload, Fire(5), Reload, Fire(18), Reload at the main menu.
Jukebox and music test
Enter "LETSBOOGIE" as a code. Press Fire(12), Reload, Fire(5), Reload, Fire(20), Reload, Fire(19), Reload, Fire(15), Reload, Fire(15), Reload, Fire(7), Reload, Fire(9), Reload at the main menu. Alternately, successfully complete all episodes in the Mighty Joe Jupiter Trilogy to unlock the "Music Jukebox" option at the Options screen.
Ending bonuses
Successfully complete the game to unlock the "Arcade Mode" option at the extra menu and the "Mirror Mode" option at the arcade mode menu.
Machine gun
Successfully complete the game in arcade mode using the pistol. Start a new game in arcade mode to use the machine gun.
Cane gun
Successfully complete the game in arcade mode using the machine gun. Start a new game in arcade mode to use the cane gun.
Shotgun
Successfully complete the game in arcade mode using the cane gun. Start a new game in arcade mode to use the shotgun.
Hyper Arcade mode
Successfully complete the game in arcade mode using the shotgun to unlock the "Hyper Arcade Mode" option at the arcade mode menu.