Cheats

• There are two cheat codes you can enter for certain advantages and unlocks in the single player campaign. At the mission select screen, input these cheats by holding both bumpers on the Xbox 360 controller and pressing a series of buttons. To unlock every level in the game, hold both bumpers and press "Left," "Left," "Right," "Right," "Y" and "Y." To equip your character with infinite ammo, hold both bumpers and press "Left," "Left," "Left," "Right," "Left," "Right," "Y" and Y." Use these cheats to visit levels you were never able to unlock before or to tear through the missions without worrying about your ammo count.
  
  

Easter Egg

• On the tutorial level, "Red Army Training," there is a way to make your unit's commissar angry enough to kill you. Instead of shooting the teddy bears on the firing range, as he asks you to after you equip your first guns, shoot at least four bottles or plates in the range. At this point, the commissar becomes angry and kills your character.
  
  

Three-on-one multiplayer

• The sniper rifles in "Call of Duty 2" are easy to use and deadly accurate, making them somewhat overpowered in multiplayer games. One way to counter this imbalance is to play a three-on-one style, where only the solo player is allowed to use a sniper. To make it more fair, you can mandate that the team of three can use only its underpowered secondary pistols. It's challenging to pick off endless pistol-wielding enemies as they try to get close enough to take you down.
  
  

Smoke Grenades and Trench Guns

• Using smoke grenades in multiplayer games can be challenging, disorienting and funny, especially in the snowbound Russian levels. If everyone in your game agrees to use the trench gun, all players will all be equipped with one smoke grenade per spawn. A good way to maximize their effectiveness is to all congregate in one house or area, throw all the grenades at once, then run around blindly trying to find each other. This is a silly way to have a good time once you're tired of playing the game competitively.