Level Cheat
During gameplay press R2, L2, Up, Down, X, L3, Circle, X, Circle, X to complete current mission with Silent Assasin rating

Level Select
To activate level select, enter this code in the Main Menu - Square, Triangle, Circle, Left, Up, Right, L2, R2

Silent Assassin Unlockable Weapons
To obtain some of the hidden weapons in the game, you must complete the missions with a Silent Assassin Rating to receive that weapon.

AK 74 Silenced Assault Rifle	Mission 9
CZ 2000 Dual Pistols	Mission 1
GK 17 Dual Pistols	Mission 10
M4 Carbine Silenced Assault Rifle	Mission 6
Magnum 500 Dual Pistols	Mission 4
Micro Uzi Dual Submachine Guns	Mission 2
Micro Uzi Silenced Dual Submachine Guns	Mission 11
MP5 Silenced Submachine Gun	Mission 8
PGM Silenced Sniper Rifle	Mission 12
Sawed-Off Shotgun Dual	Mission 5
SG220 .S Dual Pistols	Mission 7
Silverballer Silenced Dual Pistols	Mission 3

Unlock the mini gun and duel gold desert eagles
Go to level nine, The Wang Fou, incident and go in the restaurant. Hop on the elevator on the first floor and take it down to the basement. Work your way through the tunnels (you won't have your map) killing any guards you encounter. At the end there will be an elevator. Head up to the mansion's first floor and flip on your night vision goggles. Wonder around in the dark until you find stairs that go up to the second floor. Once upstairs find the office and on the desk you will find Orthmeyer's Keycard. Go back down to the basement and head back upstairs to the first floor of the restaurant. Finish the level like normal and save. Now exit to the main menu and start Mission 1 - Asylum Aftermath. Now find the first key card door. There will be a patient pacing back and forth with the mini gun, kill him and take it. You'll be walking much much slower now because it weighs so much. Find the second keycard door in the basement to get the duel gold desert eagles and finish the level with those two guns in your inventory. Now sit back and enjoy the fruits of your labor.

Coming Back To Life
When you die, there will be a black and white death sequence. If you were able to commit at least 4 consecutive head shots on 4 different guards, you will be able to resume what you were doing with a small amount of health.

Get all weapons in training
In the training level, enter the complete level code to complete the level with an SA ranking. Then, re-enter the training level to find that your weapons storage has been completely filled with all the weapons in the game.