Invincibility and items:
Pause game play and press L2, R2, L2(3), R2(3), Circle, Triangle, Square, Circle, Triangle, Square. The ninja will turn into a skeleton to confirm correct code entry. Repeat the code to turn back into the ninja while keeping the extra items. Note: Pause game play and press L1, L2, L1(3), L2(3), Circle, Triangle, Square, Circle, Triangle, Square in the Japanese version of the game.
Big head, hands, feet, and invincibility:
Pause game play and press L2, R2, L2(3), R2(3), Circle, Triangle, Square, Circle, Triangle, Square. The ninja will turn into a skeleton and become invincible. Then, pause game play and select the "Quit Game" option to return at the title screen. This time, the ninja in the background will be a skeleton. Press Select(3), L2(3), Select(3) when "Press Start" flashes at the title screen. The ninja in the background should now appear as a skeleton, except with larger versions of the regular ninja's head, hands, and feet to confirm correct code entry.
Level select:
Load the game and quickly press L2(2), R2(3) when the message "Checking Memory Card" appears. The phrase "Dels Level Cheat On" will appear to confirm correct code entry. A level selection screen will appear when game play begins. Note: All memory cards may need to be removed from the PlayStation before attempting the code. Alternately, press L2(3), R2(3).
Weaker Boss:
Pause game play during a fight with a Boss. Then, press L2(3), R2(3), Triangle(6).
All weapons:
Pause game play and press R2(3), L2(3), R2(3), L2(6). Repeat this code to select the next available weapon.
Baby mode:
Press L2(3), Select(3), R2(3) when "Press Start" flashes at the title screen.
Big heads, hands, feet:
Press Select(3), L2(3), Select(3) when "Press Start" flashes at the title screen.
Smoke bombs:
Pause game play and press R2, L2, L1, L2, R1, R2. The screen will shake to confirm correct code entry. You can you throw two smoke bombs at your enemies. Press R2, R1, L2, L1 after enabling the code for better smoke bombs.
Soundtrack:
Place the game disc in an audio CD player and play track two to hear music from the game.