Successfully complete the game. A "Cheat" option will now appear during game play at the "Options" menu.

Collect the Intel Pieces (enemy laptop computers) hidden throughout the game to unlock the cheat options. The number of pieces you have determines which specific cheats are available.

The Intel Pieces can be found in the following levels. There are a total of thirty Intel Pieces.

Level 2: 2 Intel Pieces
Level 4: 2 Intel Pieces
Level 5: 3 Intel Pieces
Level 6: 2 Intel Pieces
Level 7: 2 Intel Pieces
Level 9: 3 Intel Pieces
Level 10: 2 Intel Pieces
Level 12: 2 Intel Pieces
Level 13: 3 Intel Pieces
Level 14: 2 Intel Pieces
Level 16: 2 Intel Pieces
Level 17: 1 Intel Piece
Level 18: 2 Intel Pieces
Level 19: 2 Intel Pieces

Successfully complete the game.

Reach level 55 to unlock Prestige mode. This is a multiplayer-only mode that starts you again at level 1. You can repeat this ten more times.

Successfully complete the game and watch the entire credits to unlock the bonus Epilogue mission.

Complete Story mode under any difficulty setting.

Golden weapons are a special camo that you get when you fully complete their respective weapon challenges.You can access them by choosing the camo of the respective weapon.The weapons don't get a boost or anything alike,it's purely cosmetic.

Each weapon is unlocked in multiplayer at a certain rank.

PROLOGUE: CREW EXPENDABLE~~~ 2 Intel

1 - The first intel is located after your rope down onto the deck, where you and your team kill several enemies, enter this area and walk down stairs where you will come to a drunk man. To the right of him is an alcove, enter here where you will find two men are sleeping, and next to your first intel.

2 - The second intel is located after helicopter support is given, and you clear out a hallway of enemies. You will go downstairs where you will find an open heating vent, with the second intel on top of it.

ACT 1: BLACKOUT~~~ 2 Intel

3 - After the start of the mission, you will come to a group of small houses. Inside one of these houses, you will find 2 terroristss and the first intel on Blackout.

4 - In the house holding Nikolai, on the second floor, you will find a bathroom with the intel on top of the toilet.

ACT 1: CHARLIE DON'T SURF~~~ 3 Intel

5 - In the basement of the first house your siege, you will find a smaller room off to the left, as you come down the stairs.

6 - After some fighting, you will come to an area where you need to cross the road in order to continue. This is also where you are charged by a truck. But, when you cross this road, you'll find a group of enemies sniping at you from an above floor. Kill them, and cross the street into the right, then go up the stairs, and you'll find an intel.

7 - Head down the road to where you find the general area where the truck is crashed. You'll find a second room in the corner and after going into it's second floor, you'll find the last intel.

ACT 1: THE BOG~~~ 2 Intel

8 - After finally getting through the group of enemies in nightvision, you'll come to where Royciwiz is attacked, for a seperate achievement, kill his attacker quickly. But, go up to where you were instructed, only to go back down. You'll find that a secondary group breached a door that isn't really important, but for you it is. go through it and look around to find the first intel on this level.

9 - After destroying the enemy tanks with the Javelin, you and your team will progress into a marketplace through a cut fence. Proceed until you find an upright fridge to your left, and just next to it will be the second intel.

ACT 1: THE HUNTED~~~ 2 Intel

10 - The area where you first encounter dogs, you might want to discover it first, then restart the checkpoint. Anyways, this area contains a building with a soda machine. In this building the intel will be on a table.

11 - After venturing through 2 greenhouses, you will come to an area where to your left is a wrecked building and in front of you a few enemies. Go through the wrecked building and under a small, tarp-covered area with the second intel.

ACT 1: WAR PIG~~~ 3 Intel

12 - After the your tank runs over the car, you will be on a corner street with a building to the left. Enter the building and go to the second floor. Find the first intel in a room here.

13 - Just across from this building, on the corner, you will find the next building on a dresser.

14 - All the way down the street, in the building right in front of you, you will find the 3rd intel on the second floor.

ACT 1: SHOCK AND AWE~~~ 2 Intel

15 - You will find the first intel in a corner on the second floor where you meet the recon team.

16 - After hopping down from the building inhabiting the recon team, straight ahead is another building holding a few enemies. Clear it out and enter to find the next intel in a closet on the second floor.

ACT 2: SAFEHOUSE~~~ 2 Intel

17 - After clearing the forest and making your way up the hill to find a church to your left and a house with a sattelite dish attached to it. Make way to that house. You will find the intel on the second floor.

18 - You'll find it next to the water tower in a restaurant-like booth.

ACT 2: ALL GHILLIED UP~~~ 3 Intel

19 - When MacMillan states that there is a watch in the church, kill him and quickly climb up there after disposing of any more threats. Take the intel there and climb back down.

20 - Midway through the maze of cargo containers, you'll find a small group of terrorists huddled around a few barrels, kill them and take the intel that is on top of one of these barrels.

21 - After sneaking through the huge amount of enemies, MacMillan will acknowledge a sniper ontop of the fire escape in front of you. Take him out, and climb up the fire escape to meet a small room with the intel in it.

ACT 2: ONE SHOT, ONE KILL~~~ 2 Intel

22 - After taking out the helicopter, you need to carry MacMillan the rest of the way. You will come across a few enemies, and venture through a few buildings. After you make contact with the ground once more, you'll find a ladder next to you. Put MacMillan down and climb the ladder a few flights to find the intel.

23 - You'll come to an area where you need to put MacMillan down to ready yourself for an army of enemies. This one is tricky, but with the help of this guide, you'll be fine. Make sure as you climb out of the pool area, you find a corner secluding itself off to the left. Hold of the hord of enemies until the enemy helicopters come. Take the area I mentioned instead of the shorter way, (hopping over the white picket fence), and you will find a newly opened door. At the end of this hallway you will find the intel.

ACT 2: SINS OF THE FATHER~~~ 2 Intel

24 - After securing the area you begin at, make your way across the street into a diner. Quickly find the intel in a booth before the cinematic begins.

25 - You will chase after Zakhaev's son, who flees into a village. You will be told to take an alleyway where you will find a green car to your left and a red dumpster to your right. Take the right, and you will fight off a few terrorists. You will see a flight of metal stairs that lead to a small room. Kill the people guarding this room and take the intel.

ACT 3: ULTIMATUM~~~ 1 Intel

26 - After destroying the power tower with C4, you'll breach into an enemy base where you need to make your way to the right wall, and hug it until you come in to garage. Make your way to the back room and find the intel.

ACT 3: ALL IN~~~ 2 Intel

27 - After destroying the first BMP and making your way to the silo gate, backtrack until you find an alleyway leading behind a building, grab the intel here.

28 - After making your way through the silo gate, you will see the multiplayer map, "Countdown," but to your right you will see 3 silo hangars. Scout out the last one and find the intel in it.

ACT 3: NFITWR~~~ 2 Intel

29 - Follow Captain Price through the starting vents, and through a blood-stained bathroom to find you're given the option to take a left or right. Make your way left to find a darkened hallway with several rooms inhabiting it. Search through all the rooms to find a meeting room. Activate night vision and make your way around the table to find the intel.

30 - Once you breach the wall with the C4, go straight ahead and up the main stairs to your left. Make your way right and follow the small hallway to find a little meeting room with a map on the wall. Take the last intel.

All these perks are obtained by a certain rank in multiplayer mode.

To get Golden Guns you have to complete all the challenged in that weapon category for example LMG to get a Golden LMG Gun you would have to complete all the challenges under LMG. Note you can only have ONE Golden Gun from each category

When you kill another player with a headshot, a metal "ping" sound will play to confirm it.

Killing all three RPG enemies in the pursuing trucks in Game Over results in SSgt. Griggs saying "Success!"

In the second large containment room, run ahead of your team. There are two enemies with Desert Eagles who will try to surprise you around two corners, depending on the path you take.

If a target is moving make sure to lead it. If you are not making shots try to lead your target more. Also, if you are a skilled sniper try using the M40A3 over the M21. It has a slower reload time and rate of fire, but it has enough damage to kill a target in one shot instead of two or three. It also allows you to be less noticeable with less rounds being fired; so someone else cannot follow the tracer shot back to you. A good setup for the sniper is the Claymore perk, to alert you when an enemy is trying to close in on your rear, and either the Sleight Of Hand or Stopping Power, then Iron Lungs to give you more time to line up your shots.

Once you get the Red Dot Scope addon to your weapons, use it over the ACOG scope. The red dot will not enhance or take away anything and provides a better aimpoint on most weapons. The ACOG scope will actually add more range to your weapon, but take away accuracy which accomplishes almost nothing; especially so for snipers because it takes away range and adds nothing.

To level up quicker than usual, try to use the same gun until all the marksman and elite challenges are completed. They provide huge boosts and will quickly level you up to get new guns. However, do not use those guns yet. Just keep on the challenge until it has completed. The third phase of the challenge usually ends with 1,000 experience points and that will bump you up a rank almost in itself. Also, do not forget about the strange challenges like jumping 15 feet and surviving or falling 30 feet to your death. To get that one if not previously unlocked play the "Countdown" map and jump into one of the open missile silos. You will get instant experience points for simply dying. Also, remember to go prone and crouch to get those challenges as well.

Don't go straight for the kill as soon as he comes into view. Wait until Captain Macmillan gives the all clear. Many people don't do this and miss Zakhaev and fail the mission.

For any level, any difficulty, this hint should help you complete different levels on different difficulties easily. On anylevel where your enemies are carrying weapons like AK-47's or Desert Eagle's, always go for these, unless you already have guns with attachtments on like the grenade launcher. This would really help because the Ak-47s kill targets in one shot and this applies to the Desert Eagle if you are shooting at close quarters.

If you are on the SAS side on Overgrown you will start at the end with a building that has a mounted machine gun. Cross the bridge at this end until you reach a small shed like building. Go through here and past the exit and climb on top of the car ahead of you. Then climb onto the wall next to it and walk along it to your right until you reach a metal roof. Use this roof to snipe from or the other roof next to it. Try to avoid the gaps.

On this map, go to the of the street with a destroyed building. Go through the side door of this building and make your way to the top floor. Here, you can go prone or make your way to the far-left corner and snipe here. Always make sure you plant claymores though so you are well protected.

If you don't camp and like to run around with your sniper try to avoid using the bolt-action snipers. The fire rate for the semi-automatic snipers is higher and you have a better chance of killing someone who is engaging on you at close quarters

In the middle of the map, Crash, is a helicopter. The helicopter is split into two. Both parts of the helicopter are accessible but the smaller part can be used to snipe through a small window on a building which is a common sniping location. This means several kills can be awarded if the location you are directed at is a position for several snipers,

In story mode, Act II you will come across 'One Shot One Kill'. Once you have shot Zakhaev you will be ordered to rendevous at Extraction Point 4 and wait for your fellow teammates to meet you there. Once you reach the extraction point and you have put Cpt.McMillian down in the desired location, he will tell you to use the rest of your Claymores and C4. Use them wisely. Firstly, use your C4 and make a line of them, a fair distance away from each other and you just incase the russians get really close. Then use your Claymores and put them close to cars. This way there will be a bigger explosion which means you can take out more enemies easily.

On 'One Shot One Kill' when you are sniping by the ferris wheel, men will come in large groups near the swimming pool. Don't fire until they get pretty close because there are dogs that kill may of the russians so there is no need to waste ammo.

When being shot by a gun try to jump around and go prone until you can kill the attacker. This makes you a harder target to hit as you are constantly getting hit and is very useful against snipers.

In the level 'War Pig' you will come to find a Dragonouv and a M249 SAW. If you check the gun you have in your hand, you will have a M4A1 Grenade Launcher. If you look ahead of you there should be bus with several enemies. Use your grenade launcher to take them out from long range. Once you have used all of your ammo, make your way to the car and pick up the LMG and Sniper. After doing this, make your way to the right of the bog and kill any enemies you see. This will mean you have extra ammo with your guns that didn't need to be used straight away and that could get you out of some bad areas easily later in the level.

In the level where you get Nuked by the Opfor you are on the Mark19, a grenade launcher . When you are landing(Anywhere) and you're about two metres above the ground, aim as low as you can go, then shoot the ground. There is no explosion, just a bullet hole where you shot.

This happens very rarely, but if you jump and fall from a fairly good height precisely when the game ends (when it says Victory or Defeat) you stay in the air but you fall down very slowly.

This is a simple glitch that an be used to dominate your opponents quickly and easily. To perform this glitch, you must select the 'Crossfire' map and make your way down to the bottom end of the street and go left where you will find a building with some sort of kichen essential eg. dishwasher, washing machine. Climb on top of this and jump onto the next floor of the building from this position. This may take several attemps but it can be done. Then from here, make another jump to the next floor. Once this is done, make your way to your right whee there is a barbed wire fence below you. Walk directly above this to the next building. Then make your way to another jump. For this jump you will have to sprint to the far left corner, into the wall and then jump. You will now be in mid-air, being able to go prone and cover a good amount of the map.

Following the 'Mid-Air Domination' glitch you can get into a superb sniping position. Follow my previous glitch and stand at the edge of the building where you can see the whole street. Looking down from the building, you should be able to see a balcony. Move to your right and jump down to it. This is a superb sniping position and hiding spot.