Pandemonium

Level select:
Enter BORNFREE or FAAIAKCE as a password.
Information in this section was contributed by Dogger1044.

Invincibility:
Enter HARDBODY as a password.

31 lives:
Enter VITAMINS as a password.

Extra hearts for health:
Enter CORONARY as a password.

Immortal enemies:
Enter EVILDEAD as a password.

Rotate screen:
Enter TWISTEYE as a password. Hold L1 + L2 and press Left or Right to rotate the screen. Press Down to return to normal.

Restart without quitting:
Enter INANDOUT as a password. Allows you to quit in mid game and return to the level select screen to continue or restart on another level. To return to the main screen, repeat the quit procedure on the level select screen.

Warp body:
Enter THETHING or GENETICS as a password. Hold L2 + Circle to cycle through different body shapes. Press L2 + X to return to normal.

Switch characters:
Enter BODYSWAP as a password. Press Triangle during game play to switch characters.

Special weapons:
Enter OTTOFIRE as a password. Allows access to special weapons that never run out of power.

Pinball screen:
Enter TOMMYBOY as a password. Finish a level to reach a pinball screen. Note: this cannot be combined with the bonus screen code. Alternatively, enter KNCACKDE as a password.

Bonus screen:
Enter CASHDASH as a password. Finish a level to reach a bonus screen. Note: This cannot be combined with the pinball screen code.

Super password:
Enter ALMABHOL as a password for 31 lives and 7 hearts at the final Boss.

Turtle: Canopy Village; press Down to hide in the shell.

Dragon: A few levels;-press X + D-pad to fly, Circle to breath fire.

Frog: Fungus Grotto; jump higher.

Dinosaur: The level after Flaming Desert; press the D-pad to charge and kill monsters with your horn.

Hint: Credits bonus level:
After defeating the last boss, Wishing Engine, watch the ending sequence. When the producers, sponsors, etc. appear, at the same time you will be playing a level in the background.
Information in this section was contributed by N. Gin & Spider Pan.

Hint: Treasure 100%:
Try to get every coin (and other collectibles) in a level and you will get to play a special level. Try to complete it. If you die, you will have to collect the treasures again to reach it again.
Information in this section was contributed by N. Gin & Spider Pan.

Glitch: Funny sound when attacked:
Enter HARDBODY as a password. Go on any level using the girl and get intentionally attacked by an enemy. She should say "AAAH!" strangely.
Information in this section was contributed by N. Gin & Spider Pan.