On the last stage (Los Angeles Airport) after you get through the parking garage you come to a room with a guard in a booth to your left and a female janitor right in front of you. In this room you have two options to advance. #1) The first option is to go through the guards booth by either luring him out and then running in before the door closes, or use the door code(its either 1387 or 1687). #2) The second and eaiser option is to go into the bathroom opposite the guard booth and climb through the vent in the wall this will take you to the same place as the other way and you won't have to deal with the guard.
All items and infinite ammo
At the main menu press Up, Down, Left, Right, Right, Left, Down, Up.
Annoy Lambert
When you begin the first level (Dili, Timor) you will start off in the water. Now just sit there, or run around in the water, but don’t progress through the level. After 15 seconds after Lambert stops briefing you, he will ask you what you are doing. 15 more seconds after you reply, he makes another comment. And another 15 seconds left, he tells you to get moving because lives are at stake. Now you are free to continue your game.
Change Rate Of Fire In Multiplayer (Merc)
When playing as a merc, press and hold X to change your rate of fire (ROF) to Burst. To change it back to Auto, hold X again.
Costume Change
Beat the game on Hard difficulty mode and at the select game screen hold L + R, press black (2), white (2), Y, X, Y, X to unlock 2 different costumes for Sam.
Defeating Norman Soth
After you have climbed up the elevator cables and have gotten on top of the other elevator, crawl through the hole in the wall. Norman Soth and two other mercenaries are on the top pathways. While in the hole, there will be one guard on the top path, slightly to the right. You should be able to shoot him in the head. Then, a timer will start and you will have one minute to kill Norman Soth and his other mercenary. When you shoot the first mercenary, drop out of the hole onto the first pathway. The second mercenary will go to exactly where the you shot the first mercenary. Shoot the second mercenary in the head. Note: The second guard will be aiming at the hole, so he will not see you if you drop out of the hole. The last person to kill is Normon Soth. Start running down the pathway and turn left on the second to last walkway on the left. Look up and turn on your thermal vision. You will see Normon Soth. Get a clear shot and shoot him in the head. After that you must retrieve the smallpox box from the top pathway. If you are on the second to last pathway on the left, go up the ladder. There will be another ladder; use it to climb up. Drop off the ledge onto the pathway. Run down the middle pathway to find the smallpox box.
Easier Aiming With Pistol
To aim better with the pistol, press X to pull it out. The crosshair should appear normal. Then, press Up on the D-pad and the crosshair should become a laser sight. This makes it very easy to aim, since the laser sight is smaller and thinner than the normal crosshair. This allows fast kills and head shots. If you are in dark corners and have the laser sight on, the enemies will notice and attack you.
Easier Aiming With Sc-20k
Click the Right Analog-stick to zoom in the sniper scope, then press L to hold your breath. You should be able to get a good shot while Sam remains still.
Ensuring Stealth
It's not so much a "cheat" as it is a strategy. Even in the dark, Soth's men can see the illuminattion of your night-vision goggles in front or the power-pack on your back. To help keep from being seen, take a body (dead or unconcsious) and throw them on your back. When Soth's men are walking up to you in the dark, simply turn and face away from them and the body on your back will cover the light.
Jerusalem
On the third part of the Jerusalem stage, once you go down into the underground base all of the walkways are metal gradings, most of which you can go under. This is very helpful since there is a lot of people in a small area, you can just shoot someone and duck under the gradings. Even if they see you they can't shoot you through the gradings. So you can hide until they forget about you and keep repeating the process until all the enemies are dead.
Knocking Out Guards
To knock out a guard without using a Sticky Shocker or a Air Foil, shoot a Sticky Cam at their head. It must hit him directly in the head for the guard to get knocked out.
LAX - Room keycode
If you want to get into the security room after the car park on the LAX level instead of using the vents in the toilet or distracting the guard to get him out and then finding out you have locked yourself in the room, just type 1387 on the keypad and your in!
Passenger Car
On the train stage after you climb up from under the train you usually have to go around the outside of the train by way of the side door. But that can be very difficult since if people in the train see you the mission is over. An easier way is to turn off the lights by using the switch outside of the room where you climbed into the train from. Once th elights are off one passenger will come to investigate but if you hide behind the last row of seats you can knock him out easily. After that you can just walk through the car past the terrorists and all. (If you want to once you get to the other end of car you can lure the terrorists to you by whistling and then knocking them out. Just make sure they don't trip an alarm.
Prince Of Persia References
On the mission when you are on the train, look in the second car where the guard is located. Knock him out then go behind the fenced door. Look down you will see a magazine featuring Prince Of Persia. Also, on the third level when you are in Paris on the train, at the beginning there will be a room with an engineer. Knock him out. On the floor of the room is a Prince Of Persia strategy guide.
Stealth
To move quieter, crouch down and walk slower. This will make your steps softer, and keep you undetected to a limit. To decrease your chances of being seen, shoot out the lights with your gun. Be careful, as if there is an enemy is under that light they may see you shooting it out.
Whistling
To whistle, press Black. This will usually make a guard approach the sound. Note: Hide in a dark area and whistle, then jump the guard when he stops.