At the level selection screen, hold Select + Square + Circle and press Right(3), Up, Left, Down, R2.
Pause the game, then hold Square and press Left, Right, Up, Down. Note: A perfect score cannot be achieved with the use of this code, as your character will be counted as spotted once in the final score when this code is used.
At the item selection screen, press Square(3), Circle, Square, Circle(2), Left, Up, Down, Right, R2(2).
At the item selection screen, hold R1 + Square and press Right, Down, Left, Up.
While playing a game, hold Select to display the map, then press Circle(5).
Enter the custom mission screen in the mission editor, then hold R2 + Circle and press Up, Down(2), Right, Left(2).
Enter the mission settings screen in the mission editor, then hold Circle and press Up(2), Down(2), Left, Right.
Enter the edit mission screen in the mission editor, then highlight the "New Mission" selection. Hold L2 and press Circle, Square, Left, Right, Circle, Square. If you entered the code correctly, you will hear a sound. -From: Musashi9848@aol.com and wolferian@hotmail.com
At the level selection screen, hold Square + Circle and press R1, R2, L2, L1, Up, Down, Left, Right, Select. Alternatively, successfully complete the game with both Rikimaru and Ayame.
Simply advance in the game to get more options in the mission editor. As your character reaches new levels with new tilesets, the same tileset will then be available in the editor.
If you are in certain levels (Quarantine Village, Laborers), you do not need a grappling hook to get on to the roof of a house. Run up to the wall, face it, and jump. Your character will jump twice the normal height of the usual jump and land on top of the roof without hanging on the side.
Hit an enemy who is not aware of your presence in the head with a blow gun dart to automatically kill them.
You do not need to pull out your weapons to perform a stealth kill. Run to the enemy and press Attack. Your weapons will instantaneously be drawn out, and you will perform the stealth kill.
You can get the different stealth kills by being in the correct position in relation to the enemy.
Sneak up from behind.
Sneak up from behind and crouch.
Jump on enemy, while pressing Attack in mid-air.
Sneak from the side.
Sneak from front (or wait for them to turn around into you). Note: This must be timed perfectly.