Successfully complete the game on the easy difficulty setting to unlock the "Big Head", "Ricochet", "Head Shot", and "Ricochet All" cheat options. Successfully complete the game on the normal difficulty setting to unlock the "Shrink Shot" and "Dead Eye" cheat options. Successfully complete the game on the hard difficulty setting to unlock the "Big 'N' Small" cheat option. Note: You do not have to play the entire game on all three difficulty settings to unlock all cheat options; you only need to complete the last level on each difficulty setting.
Successfully complete the Russian campaign to unlock the Making Of 1 FMV sequence. Successfully complete the British campaign to unlock the Making Of 2 FMV sequence. Successfully complete the American campaign to unlock the Making Of 3 FMV sequence.
There are two secret areas in this level. The first is found at the first house where you have to exit your tank. Go to the barn door and jump at the wall to the left of it. You will go through the wall into a room with a giant chair and a very small door with a green light shining out. There are also two health packs in the room. The second secret area is at the second house. Go inside and clear out the house. In the back room on the right is a window where you can shoot the machine gunner that was shooting at you while you were coming into the house. Go back downstairs and outside. Jump over the sandbags and onto the barbed wire. Follow it to the house. You will go through the wall and down a hallway. At the end is a room with a Nazi UFO and four health packs.
First, go to the building on fire and get the health pack. Then, wait until the tanks kill everyone and blow up the building entrance. Go inside and get the two health packs. Kill the man with a rocket launcher. Go outside and stand in front of the M12. It will not go anywhere. Get to where you can snipe enemies with the M1 Garand and where they cannot see the M12. Go get the health pack by the city gates and pick up any left over from the battle. Around the corner is a room with a rocket launcher and a health pack. Down the street are more rocket launching Nazis. Stand in front of the M12 and snipe the Panzerschrecks again. Ease around the corner and there will be a building where about twenty five enemies will come out from. Set and snipe them. Go to the end of the street and into the building to kill two more anti-tank soldiers. Go in the basement and get a checkpoint. Then, go through the tunnels and get to the machine gun. Kill all the Nazis until the theater is blown up. Once they are all dead, go down another set of stairs and out the door. There are two Nazis with rocket launchers where the machine gun is located. Kill them and go down the sewers to complete the level.
Go out of the building that you started at. Go up the hill outside, then go into the trench on your left until you reach a hill. Turn right, clear out the pillbox, then get out of the pillbox and go straight. Clear out the next pillbox. Go back out of the trench and turn to the right. There will be another trench here. Do not go into it yet. Pass it, turn right, and go downhill into another trench. There should be a path leading left as you enter the trench. Follow it and you will find the MG42, which is a machine gun that you can carry that is just like the stationary guns that were shooting you earlier.
Start the mission. Back up slightly and turn to your left. Find the tree near the road with no leaves (just branches). Face that tree, then drive up the right side of it, going off the road that you were on. Turn left and follow the dirt path in the snow that leads away from the mountain. After the path turns, look in the distance to find a strange object. Drive towards it to reach a giant hollow apple, with a UFO inside.
In Surrender At Aachen (the third mission in the American campaign), go through the door and kill the four Nazis (grenades are useful). Go to the area straight from the door that you came through. There will be a MP-40 and a teddy bear here. Pick up the teddy bear and you will receive health and a message stating "The Bear is adorable".
On the multi-player map The Square, go towards the building with no equipment in front of it. On the left side there is a wall. Jump onto the wall then jump onto the dirt. Next, jump down on the other side and you are now out of The Square. Other players cannot see you, but you can see them.
When you get up to the sniping area, crouch down in the window. There will be some ammunition and health in the corner if needed. Get it if desired, then snipe the first wave of soldiers with normal guns. When your "comrades" say that there are Panzershrecks, concentrate all of your fire there. Do not worry about the regular soldiers because they cannot aim well. Shoot the Panzershrecks until you see a man running up the road with a heavy machine gun. Shoot him then go to the left window and continue.
On the first tank level in the Russian campaign, it is best to use first person view to shoot the Nazis that have Panzershrecks and MP-40s. The MP-40s cannot hurt you, but are annoying. If you use third person view, you will usually miss.