Level select

Pause the game, hold L1 and press Triangle, Up, X, Down. If you entered the code correctly, you will hear a gunshot. Then, select "Exit" to return to the main menu with a new option.

Debug mode

Pause the game, hold L1 and press Down(2), Triangle. If you entered the code correctly, you will hear a gunshot.

Invincibility

Pause the game, hold L1 and press Down, Up, Left(2), Triangle, Up, Right, Down. If you entered the code correctly, you will hear a gunshot.

Infinite lives

Pause the game, hold L1 and press Triangle, Circle, X, Square. If you entered the code correctly, you will hear a gunshot.

All weapons

Pause the game, hold L1 and press Square, Circle, Up, Down, X, Square. If you entered the code correctly, you will hear a gunshot.

All weapons and infinite ammo

Pause the game, hold L1 and press X, Triangle, Circle. If you entered the code correctly, you will hear a gunshot.

Refill health

Pause the game, hold L1 and press Square, X, Triangle, Circle. If you entered the code correctly, you will hear a gunshot.

Skip to last place of death

Pause the game, hold L1 and press Square, Circle, X. If you entered the code correctly, you will hear a gunshot.

From,
Andrew Craven