Go to the start menu and select "Enter cheats" then enter these cheats:
[B], [B], [X], [A] - Superman
[B], [B], [X], [B] - Team Superman
[B], [B], [X], [Y] - Autowin
[B], [B], [X], [X] - Refill ammo
Unlock Awards and Medals
Purple Heart - Get wounded or killed in action
Bronze Star - Get 15 kills
Silver Star - Get 20 kills
Distinguished Service Cross - Get 25 kills
Congressional Medal Of Honor - Get 30 kills
Have a rifleman, a demo or support, and a sniper.Use your sniper when the threat indicator indicates that there are men from afar (yellow). Use your rifleman when it turns orange, and your support or demo when it turns red.
When using the bazooka in the lying down position, remain in one spot and your character will be crouching. If you begin to crawl, once you stop your character will continue to crawl, but not move anywhere. Once you are lying down, roll one way or the other, and your character will begin to float or slide in the direction you roll.
Glitch: Pagoda: Lay Down Under Water
Follow the directions to perform the "Pagoda: Get on top of the main bridge" glitch. Once on top of the bridge, look down and line yourself up with the river. Turn around and lay down, then crawl backwards off the bridge. If done correctly, you should land in the middle of the river, still laying down. You will have a clear view of the valley in front of the bridge, and be able to shoot at anyone, but nobody will be able to see you. Note: Be careful when using a grenade launcher. The grenade will detonate on the surface of the water at times.
Go to the main bridge and look at the large rocks that are in the river. They are about fifty steps from the bridge. Get into the water and crouch down next to the biggest rock that you see. Make sure that you are on the right side of the rock looking towards the red hut, and not the bridge. While you are crouched, move your man around close to the rock and at the same time keep tapping [Down]. When you find the glitch, your character will lie down next to the rock in the water. You have a perfect view of the red hut. People cannot see you, but you can shoot anyone. The silent sniper rifle is recommended to keep other players from learning your location. Make sure you have someone covering the forest on the right -- if people get close they will be able to see where you are. Have someone else on the bridge covering the right side of the hut and you will always win.
Glitch: Sniper Zoom on Any Weapon
Start a two through four player mission. Immediately kill one of your friends when you start. The killed player can now cycle through the other players' screens, and can zoom as if the gun where a sniper rifle. Have whoever wants to use the dead person's screen use it. The dead player can control the zoom, while the other player moves the character. Note: This is extremely useful if the person that operates in the dead player's screen has a heavy machine gun.
Take out your grenade launcher out and zoom in. Go to your regular gun, and as soon as you get to it, zoom, then zoom again to get a little more closer.