Remove your memory card then turn on the PlayStation. When the screen says "Checking Memory Card" quickly press L2, L2, L2, R2, R2, R2. The worlds "DELS LEVEL CHEAT ON" should appear. Start a new game to access the level select menu.

This simple code allows you to weaken bosses to the point where they will only be able to sustain a few more attacks.  During any boss battle, simply pause the game and press L2 3 times, R2 3 times, and then the triangle button 6 times.

If you use this code on the spider boss at the end of the catacombs level, a giant treasure chest falls on the arachnid to squash it (damaging it severely to the same extent) and the words "EAT THIS!" flash across the screen.  Quite funny!

At the main menu press Left, Right, Right, Up, X, X, Square.

While the game is paused press R2x3, L2x3, R2x3, L2x6.

As START flashes press L2,L2,L2, Select 3x, R2,R2,R2.

At the title screen when "PRESS START" flashes simply press SELECT(3x),L2(3x),SELECT(3x)Then the ninja should have a big head