Score Display At the main menu, press Left(2), Right(3), Left, Right, Start on a standard controller or light gun D-pad. If you entered the code correctly, a "0" score will appear at the top left portion of the screen. (Thanks to HAROKoRn13@aol.com)

Infinite Continues Successfully complete training and boss mode. Then the "Continue" option will change to "Free Play". (Thanks to HAROKoRn13@aol.com)

Infinite Super Ammunition Successfully complete training mode with a five red star rating on each stage. Then, infinite super ammunition that kills with one hit will be unlocked. (Thanks to HAROKoRn13@aol.com)

All Items Successfully complete training mode on all five difficulty settings to receive all items in original mode. (Thanks to HAROKoRn13@aol.com)

Bonus Room Successfully complete the game without any hostages being killed. (Thanks to HAROKoRn13@aol.com)

Bonus Options in Boss Mode Successfully defeat and obtain a ranking for all bosses in "Boss Mode" to unlock "Emperor" and "Fight All Bosses" options. (Thanks to HAROKoRn13@aol.com)

Napalm Gun Kill the first three zombies in level 1 with perfect head shots. If done correctly, the napalm gun will appear on the ground. (Thanks to HAROKoRn13@aol.com)

Flamethrower In Level One (Arcade Mode - One Player), kill ALL zombies with perfect headshots, rescue all civilians, defeat the boss without getting injured, and don't get hit by anything. The Flamethrower will then appear. (Thanks to CoNtorSPoo@aol.com)