Pause the game. Highlight "Sound FX" option at the pause menu. Then press: Triangle, Square, Circle, X, Triangle, Circle, Square, X, Triangle, Square, Triangle. (A tone confirms correct entry.)

Restore life Pause the game. Highlight "Sound FX" option at the pause menu. Then press: X, Triangle (x2), Circle, X, Triangle (x2), Circle, Square (x2), X. (A tone confirms correct entry.)

Alternately, prior to game play, enter "VONLUX" as a password.

Pause the game. Highlight "Sound FX" option at the pause menu. Then press: Triangle (x2), Square, Circle, X, Triangle, Circle, Square (x3), X. (A tone confirms correct entry.) The red bar at the top of the screen should shorten, allowing more time to explore.

Pause the game. Highlight "Sound FX" option at the pause menu. Then press: X, Square, X, Triangle, Circle, Square, X, Circle, Triangle (x2). (A tone confirms correct entry.)

Pause the game. Highlight "Sound FX" option at the pause menu. Then press: Square, Circle (x2), Triangle (x2), Circle, Square (x2), Triangle, Square. (A tone confirms correct entry.)

Pause the game. Highlight "Sound FX" option at the pause menu. Then press: X, Triangle (x2), Circle, X, Triangle (x2), Circle, Square, Circle, X. (A tone confirms correct entry.)

Pause the game. Highlight "Sound FX" option at the pause menu. Then press: Triangle, X, Circle, Square, X, Square, Circle, Triangle, X, Square, Circle. (A tone confirms correct entry.)

Alternately, prior to game play, enter "HUIBON" as a password.

Pause the game. Highlight "Sound FX" option at the pause menu. Then press: Triangle, Circle, Triangle, X, Square, X, Circle, Square, Triangle, X, Square. (A tone confirms correct entry.)

Pause the game. Highlight "Sound FX" option at the pause menu. Then press: Square, X, Circle, Triangle, Circle, X, Square, Triangle, Circle, Triangle, Square. (A tone confirms correct entry.)

Enter "ACTIVATE" as a password.

To play in a particular world, enter its password below.

World    Password
1        EAUGXTAH
2        DHTKARIZ
3        ZMZZUJKJ
4        PFXMNHHR
5        CBKWSYMY
6        IETDIMGV
7        WTZVUGBX

Enter "COMMANDO" as a password.

These are strategies for beating the bosses to each world:
Prehistory-Bear: Equip your large club and, this only works if he's on all four legs, whack him in the head. Switch to a lighter weapon and dodge backward until you're out out of his range. Wait 10 seconds for him to cool off, then repeat about 4 times.
Roman-Bull: This guy's kinda tricky. Arm your axe and wait for him to charge you. When he's about 2 seconds away from hitting you, use your forward attack. Repeat this process about 4 times.
Japan-Dragon: Evade his his fireballs and slash his neck when he rears his head back. Repeat until he is dead.
European Middle Ages-Demon: You can use the Magic Spell but I recommend the crossbow. Shoot at him when he stops moving, but be sure to avoid his projectiles. Grab the nearby battery if you need extra health.
Conquistador-Aztec King: This guy is a piece of cake. Shoot him 3 times with the pistol. Be sure to reload before he can get near you.
Western: There really isn't a boos here, just a lot of guys shooting at you at once. Use lots of dynamite and shotgun ammo.
Modern Wars-Tank: Pretty strait forward, use the bazooka. Its machine gun attack is impossible to avoid, but you can dodge its missiles.
Future-Cyborg Alien: This guy is a nasty little sucker! The only weapon that even dents him is a thermal grenade, so make sure you have a lot. Be sure to avoid its lasers, and don't let it get too close.
Beyond Time-The Virus: The virus is very fast, so don't unload all your ammo at once. Wait until he is fairly close and isn't moving too fast, then nail him with a crystal. He doesn't do a lot of damage, but if he hits Betty, you will get hurt. Note that you can move vertically in this arena.