Nightmare Creatures
# A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
Cheat mode
Enter Left, Up, Triangle, Down, Triangle, Triangle, X, Up or Left, Up, Triangle, Down, Circle, Triangle, Square, Down as a password. Then, infinite continues, level select, and play as a monster options will be available. Alternatively, enter Left, Up, X, Square, Down, Triangle, Square, Down as a password.
Debug mode
Enable the "Cheat mode" code, then press L1(3), R1(3), L2(3), R2(3), Select. If you entered the code correctly, you will hear a sound.
One-hit kills
Enable the "Cheat mode" code, then press L1, R1, L2, R2, Select. If you entered the code correctly, you will hear a sound. Now it will only take one hit to kill a creature.
Small creatures
Enable the "Cheat mode" code, then press L2(2), R1(2), L1, R2, Select. If you entered the code correctly, you will hear a sound. Now start a game, pause, and enable the "Reduce" option to shrink the creatures in the game.
Blurry mode
Enable the "Cheat mode" code, then press L1, L2(2), L1, L2(2), L1, Select. If you entered the code correctly, you will hear a sound.
Music select
Enable the "Cheat mode" code, then press L1(4), R1(3), Select. Then, pause the game, highlight the "Current Track" option, and press Left or Right to select a song.
Level select
At the title screen, press L1(2), L2, R1(2), R2, Select. If you entered the code correctly, you will hear a sound. Now start a game and pause to access an option that allows you to choose any level.