Grenade launcher
Using a grenade launcher in close range will kill you in one shot. Try and use the manual target button to lure the explosives away, so Gabe cannot get caught in the explosion. The same should be done with grenades. Throw the explosive and use the same target. The grenade will land there, catching anyone in the blast

All weapons and unlimited ammunition
Pause game play, highlight the "Weapons" option, then hold [Right] + [L2] + [R2] + [Circle] + [Square] + [X]. Note: Only the weapons normally available during the current level will become selectable. Note: Hold [Select] + [L1] + [L2] + [R2] + [Circle] + [X] in the PAL version of the game. Hold [L2] + [R2] + [Square] + [Circle] + [X] in some CD-R versions of the game.

Level select
Pause game play, highlight the "Select mission" option, then hold [Left] + [R1] + [L1] + [Select] + [Square] + [X]. Note: Hold [L1] + [L2] + [R1] + [R2] + [Square] + [Circle] + [X] in the PAL version of the game.

One hit kills
Pause game play, highlight the "Silenced 9mm" selection under the "Weapons" option, then press [Left] + [L1] + [R2] + [Select] + [Square] + [X]. Gabe will say "Understood" to confirm correct code entry. A single shot anywhere on the body of an enemy with any gun will kill instantly. Repeat the code to disable it. Gabe will say "Damn It" to confirm correct code entry. Note: Pause game play, highlight the :Objectives" option, then press [Right] + [L1] + [R1] + [R2] + [Circle] + [X] in the PAL version of the game.

Expert mode
Highlight the "New Game" option on the title screen, then hold [Left] + [L1] + [R2] + [Select] + [Square] + [Circle] + [X]. The phrase "Damn it" will be spoken to confirm correct code entry. Note: Hold [L1] + [L2] + [R2] + [Square] + [Circle] + [X] in the PAL version of the game.

Weaker opponents
Pause game play, highlight the "Map" option, then press [Right] + [L2] + [R1] + [X]. A laugh will confirm correct code entry. Note: Hold [Right] + [L1] + [R1] + [R2] + [Circle] + [X] in the PAL version of the game.

View FMV sequences
Locate the area in level 1 where your character jumps through a window to get to the elevator. Go straight and jump over the boxes. There are pictures on the wall that resemble doors. Approach the middle picture where the Flak Jacket is located. Then, game play and enable the "Weaker opponents" code. The game will resume in a movie theater. Walk into the entrances to the theater (the curtains) to watch the FMV sequences. Press [X] to advance to the next FMV sequence or press [Start] to exit. Note: Hold [L2] + [R2] + [Select] + [Square] + [X] in the PAL version of the game.

Only half of the game's FMV sequences will be shown. To see the rest of the FMV sequences, set the beacon on the bomb in the lower level of the subway.

Shooting with the viral scanner
After getting the detonation codes from Ericsson in the Pharcom warehouses and the FMV sequence is over, kill him. This will not end the mission. Take the viral detector. "Viral detector bullets" will show up on the screen. When you use the viral scanner, press [X] and you can shoot a bullet into walls and floors. However, no windows, guards, or explosives can be shot with the viral scanner.

Get the detonation codes and take the viral scanner. Then, use any weapon you have to kill him. You will not fail a parameter.

Burn people with taser
Shoot someone with the taser and hold it for at least five seconds. They will scream and catch fire. You can aim, target, or just shoot -- it does not matter.

Destroying the helicopter
A critical element of destroying the chopper on the rooftop seems to be hitting its undercarriage (the white underside). This can be difficult after the chopper starts "smoking" and performs its deadly second attack pattern. A great way to hit the chopper (and deal with the Arctic terrorists) is to use the manual-aim-sidestep maneuver from around the corners of the radar assembly base. Duck out and fire. The chopper hovers behind the radar for a good ten seconds. By doing this, the chopper cannot hit you with its guns, but you can happily shoot its belly (thereby killing it), or at the heads of scampering terrorists.

To easily destroy the helicopter, shoot it awhile with a PK-102 so that it starts to smoke. It will shoot you while hovering over a radar. Arm yourself with an M-79 grenade launcher and shoot its belly twice. This will also kill the arctic terrorists. The helicopter will now be on fire. Take out your PK-102 again and shoot it again. After a few shots, the helicopter will be destroyed.

Killing Vladamir Gabrek
After you booby trap the first fuel tank, turn right after killing two guards and another in front of a gate that is along the way to the motion sensor power relays. Go to that gate and look at it. Then, turn right and face the building it is short enough to jump on. Go across until you are on the other side of the gate. Jump off and walk down the concrete, but stop at the corner of the building. There is a guard in a doorway. Kill him silently, then keep going. Soon you will see Gabrek and his escort walking away from you. Throw a gas grenade in the middle of them. Take the key and Gabrek's 9mm.

Mckenzie Airbase Exterior: Suicide
In the Mckenzie Airbase Exterior mission, you have to turn the ignition on a base supply truck. Doing this causes it to crash into a building and explode. You kill yourself, jump on the truck before it leaves.

Freedom Memorial: Defeating Girdeux
In level 5, Freedom Memorial, most of the time you can defeat Girdeux by manually aiming at the gas tank on his back. If you a harder challenge, target lock on Girdeux and shoot him with any automatic weapon. This also works with the shotgun. Shoot him for a while. He will eventually explode. If you want this to go fast, shoot him a few seconds after he explodes and he will explode again. Do this enough times and you will win. For an even greater challenge, try it without target lock.

Get a sniper rifle, then lure Girdeux onto the ground floor so that the base of the statue is between you and him. Zoom in on his fuel tank with your rifle. Shoot one round every few seconds. The statue base keeps him from drawing a good bead on you, and your evenly spaced, accurate shots should keep him too busy with recovering from the explosions to even point his weapon at you.

Highlight your shotgun and get ready. Aim at Girdeux and shoot when he is facing away from you. This should result in a one hit kill.

Georgia Street: Bad words
Enable the "All weapons and unlimited ammunition" code. Equip the grenade and go to the place where you go to help the Bomb Squad. Throw the grenade to the sniper above the building. However, do not throw it directly to him. Have it under him. Take cover, and he will say some bad words. If it does not work at first, try it higher or lower.

Defeating Kravitch
Get the M79. Go to the room where you are supposed to kill him. As soon as you see him, shoot the M79.

Defeating Rhoemer
Quickly run to the right ledge. Take the gas grenades. Crouch and throw a gas grenade at Rhoemer -- he cannot shoot you.

Defeating enemies
You can kill everyone in the game except Girdeux (the person with the flamethrower in the Freedom Memorial), who you can finish off with three shots to his backpack with a shotgun; and Rhoemer in the final level, who can only be killed by a gas grenade.

CBDC agents turn bad
When playing the first stage of Syphon Filter, wait for a CBDC agent to be killed. Once the CBDC agent is dead, approach the corpse and shoot it in the head a few times. All the CBDC agents will turn against you. Note: You can not kill the CBDC agents without destroying the mission.

Make the CBDC agent run
If you want a CBDC agent to move, aim at his head so the "head shot" message appears. He will run away.

Lazy CBDC agents
You can make CBDC agents stop shooting at the enemies by standing in front of their weapon.

Killing CBDC agents in the Georgia Street level
Enable the "All weapons" code. Complete all the objectives you can before you have to enter the subway. Kill all terrorists on the streets and blow up as many objects (lights, windows, cars) as possible and turn as much of the city black as you can with the unlimited grenades and M-79 rounds. Then, go to where you first started and carefully aim your M-79 at the CBDC agents' heads -- make sure it is a solid head shot. The Grunts may be bobbing their heads looking for targets. Shoot them all in the head and you will not fail a parameter.

Killing terrorists
On the Georgia Street level, equip your Tazer and make sure you are near CBDC agents. This is best done when you first begin the level. When a terrorist comes down the street, zap him and hold [Square] the entire time until a CBDC agent kills him and he falls down. If you kept [Square] held the entire time, the terrorist will be on the ground, shaking.

Survive burning
Quickly press [Start], then press [Start] again after catching on fire. You will be hurt, but still alive.

When you catch on fire, quickly roll. You will be hurt but you will not die.

See enemies burn
Use the taser and press [L1] to aim. Make sure that you get a "head shot". Fire the taser and release [L1]. You will see the shot from the enemy's point -of-view. Keep holding the fire button to see the enemy smoke up and burn.

X-ray vision
The virus scanner may be used to look through the walls to find enemies.

Taser
You can kill anyone with the taser except for the second Boss. If the enemy is wearing a flack jacket, then shoot them in the head.

Getting an M79
Walk into the first building and go into the first passage until you come to another passage-way blocked by two crates and a man inside that is shooting at you. Kill the man, enter the room, and go through the window. Start walking around the corner on the outside of the building. Kill the man, jump onto the dumpster, jump onto the fire escape, then glide across the pole. The M-79 will be in the case.

Remote-controlled missile launcher
Destroy all the cars on level one. Go down the elevator to the subway control section and look around. The message " remote " will appear at bottom of the screen when you get it.

Getting through the subway
Go to the opposite end of the subway after it explodes. Use the flashlight on the left of the tracks to find the C-4. Get the C-4, then go to the right hand side. Look up to see the upper level. Press [Triangle] to climb onto the red crate. Press [Triangle] to keep climbing up through the debris until the top is reached. This is the only way to exit the lower level.

Getting past the last two guards in the catacombs
After killing the other guards and reach the last two guards do not kill them. Sneak up by holding [X] the entire time. When you get directly behind them, quickly make a right. Release [X] and go. When you get to the place where you can turn left, do so and go all the way. Note: you may need to kill one or two more guards after you turn right. When you get to the last guard you should hear the door open. Kill the guard and finish it off.

M79 grenade launchers in level 1
Go out the window in the bar into the back alley. Look up and to see two fire escapes. Climb onto the dumpster and get onto the fire escape opposite the bar first, then jump up to the pipes and go hand over hand to the other fire escape. Be careful, because two terrorists will run out to shoot half way across the pipe. After taking care of them, drop down onto the fire escape and open the box for the grenade launcher. This makes the grenade thrower in the subway section much easier to handle.

Museum gates
Find the card keys to get through the gates in the museum. Check all the guards and people that are killed; they usually carry card keys. For the gate in the Rocket Room, shoot the control panel on the third level that keeps sparking while your character is standing on the elevator to reach to that level. The man with the card key is up there.