The cheat menu is unlocked after completing the game on any difficulty.
Cheats are unlocked by collecting enemy intel, which look like laptop computers, that are hidden throughout the campaign.
Note: You can't get achievements while using cheats.
The amount of intel and cheats unlocked correspond as follows:
2 Pieces - "CoD Noir" : The game turns to black and white.
4 Pieces - "Photo-Negative" : The game colors become inverted.
6 Pieces - "Super Contrast" The game's contrast increases.
8 Pieces - "Ragtime Warfare" : The game feels like an old silent movie.
10 Pieces - "Cluster Bombs" Five additional frag grenades spawn from the explosion of one frag grenade.
15 Pieces - "A Bad Year" : The enemies explode into tires when killed.
20 Pieces - "Slow-Mo Ability" : The game slows to 40% of its normal speed.
30 Pieces - "Infinite Ammo" : You have an unlimited amount of bullets/ammunition.
The following is a guide to find each piece of intel in the order that it appears:
Level: Crew Expendable
• Intel #1: This intel is located in the room the drunk soldier comes out of when you first enter the ship, near the two sleeping soldiers.
• Intel #2: After clearing the deck, you'll head into the hold of the ship. You'll eventually reach the cargo holds. After Captain Price throws a flash-bang through a door, follow him through and head to the bottom of the steps. The laptop is on the floor near the hole in the metal grate.
• Intel #3: At the beginning of the level, you'll come to a few Russians standing outside a shack overlooking the swamp. Head into the shack to find the laptop.
• Intel #4: On the second floor of the building where you need to use night vision goggles, check the bathroom before you rescue Nikolai. The laptop is near the toilet.
Level: Charlie Don't Surf
• Intel #5: After reaching the target building at the beginning of the level, head downstairs into the room filled with weapons. A small room through a doorway from this room will have the laptop near a television set.
This laptop is easy to miss if you're not looking for it.
• Intel #6: After exiting the first target building, stick to the right as best you can. You'll bypass the firefight amongst the corrugated steel. If you stick to the right, you'll eventually come to a building with a light blue interior and stairs leading up. The second floor holds the intel. If you get to the point where you fight someone in a technical (pickup truck with a machine gun in the back of it), you've gone too far.
• Intel #7: After defeating the soldier in the technical (pickup truck with a machine gun in it), you'll cross the main road. It's easy to miss, but one of the buildings on the right will have steps leading up to the second floor. Look for a poster of a red fist on the wall with a star above it; the stairs will be immediately next to it. Head up them to find the third piece of intel in the level.
Level: The Bog
• Intel #8: In the first building that you enter, you'll be tasked with using the enemy machine gun emplacements against them. After doing so, return to the hallway of the second floor, where your soldiers will breach a door. Head through the door to reach the first piece of intel.
Check behind these boxes for the intel.
• Intel #9: After using the Javelin to destroy the enemy vehicles, you'll head into the alleyway between you and the Abrams. Check behind a palette of cardboard boxes in one of the alleyway's corners to reach the next piece of intel.
• Intel #10: Near the beginning of the level, you'll be hunted by a helicopter. After entering the basement of the building nearby, fight your way to the first floor and out the front door (where you'll likely encounter a flash-bang grenade attack). After the flash-bang, head outside and into the building on your right to find the laptop.
• Intel #11: Eventually you'll head through two greenhouses. When Price tells you "The helicopter's making another pass!", look around for the tin roof between the second greenhouse and the barn where the Stingers are located. The laptop is underneath that roof.
Level: War Pig
• Intel #12: Near the beginning of the level, you'll escort the tank out of the bog. After it crushes the abandoned car, stick to the right side of the street. One of the buildings there will have a second story. Take the stairs up and access the laptop to find the intel.
• Intel #13: When you find the first piece of intel, jump out of the building and cross the street. To the southeast, you'll find another two-story building. In one of the rooms here, you should find a cot with a laptop on it.
• Intel #14: Near the end of the level, you'll reach an alley full of cars, overlooked by a pair of machine guns. Fight your way to the MGs. The room that they're in will have the laptop.
Level: Shock And Awe
• Intel #15: The halfway mark will be reached in the same room where you encounter the stranded recon team on the second floor of a building. Look to their right and you'll see the laptop behind some barrels.
• Intel #16: After you meet the recon squad, you'll jump down to a firefight with a lot of troops. Some of them will be firing at you from the windows of the second story of a building. Fight your way into the building, climb the stairs to the second floor, and look into the bathroom there for the intel.
• Intel #17: After heading up the forest path at the beginning of the level, you'll spot a large building on the right. After clearing it out, head up to the top floor and find the laptop on a dresser near a mattress on the floor.
• Intel #18: There's a large restaurant/bar style building next to the water tower. The laptop is in plain site in one of the booths on the first floor, but can be difficult to spot due to all the weapons it's on.
Level: All Ghillied Up
• Intel #19: After eliminating the spotter in the square tower of the church, you'll enter the building itself. Climb up the ladder to the tower where he was stationed to find the intel.
• Intel #20: When you reach the maze of cargo containers, there'll be a group of soldiers sitting around a few barrels off to the right. Macmillan will lead you around them, but the laptop is on the barrels, meaning that you'll have to start a fight to get to it. You can chuck a grenade into the middle of the soldiers, grab the laptop, then reload if you die.
• Intel #21: After shooting the sniper off of the fire escape, walk up to where he was stationed and jump through the window to nab the laptop.
Level: One Shot, One Kill
• Intel #22: After Macmillan is wounded, start making your way through the level. Eventually you'll reach a building with soldiers and a couple of dogs inside, on the second floor. Clear the building out, make your way outside, then set Macmillan down and climb up the fire escape to find the laptop.
• Intel #23: When you reach the end of the level, you'll be tasked with setting Macmillan down and letting him provide sniper support. Survive the first waves of enemies. When the helicopters come to unload more enemies, though, you can head up into the alley to the right of where you're probably facing. One of the back doors to the building on the right side of that alleyway will have opened, revealing the laptop.
Level: Sins of the Father
If you miss this intel before the scene shifts to daylight, you'll have to reload the level to get it.
• Intel #24: After you get on the dumpster to take out the snipers in the tower, cross the lot to the diner, head inside, and nab the intel off a table in one of the booths. You have to nab it before Price orders everyone to put on the Russian uniforms and the scene changes to daytime.
• Intel #25: After Zakhaev runs off into the village, you'll follow him, then duck off into an alleyway to your left. Eventually you'll fight enemies on the other side of a metal fence, then fight off enemies on top of a rooftop. There's a building here with a set of steps leading up to its second floor; head up to find the laptop.
• Intel #26: After you destroy the power lines and cut through the gate, you'll come to a walled-in area where you fight multiple enemies, including troops that rappel down from choppers. After the fire drops down a bit, cross the yard and head into the building on the opposite side. In one of the small rooms on the first floor you'll find the laptop.
Level: All In
• Intel #27: As you proceed through the base, you'll head to the right and assault a gate that Price will blow up. Before heading through, check the alleyway behind the building to the right of the gate to find the intel.
• Intel #28: During the firefight with the two BMPs (or after it), make your way to the southeastern corner of the silos. There'll be a hangar there with a laptop on the ground.
Level: No Fighting In The War Room
• Intel #29: After dropping into the bathroom, take the left exit and head past the locker rooms and dorms. You'll eventually come to a darkened conference room on the left side of the hallway; the laptop is on the table inside.
• Intel #30: When you breach the missile control room, head up the stairs and enter the conference room there. The laptop will be on the table.