"Halo: Combat Evolved" Cheats
You can unlock special items by using cheats in the first "Halo" game, "Combat Evolved." Normally, you are only allowed to carry two weapons at a time, but a cheat allows for three. On the first level, head past the bridge to the first save point before the name of the level fades from the screen. In the hall area, you can then pick up two weapons along with the gun you already have. You can also get unlimited rockets for your rocket launcher weapon if you play the multi-player stage "Assault on the Control Room" by going to the "Rolling Thunder" area and firing a shot as the second player enters.
"Halo 2" Cheats
You can get an unlimited supply of camouflage by finding the Envy Skull and heading to a save point while wearing camouflage at the time. Rather than saving here, choose to revert to where you last saved. Save your game, turn the system off, and then reload your game. You will now have all the camouflage you want. To refill your ammunition when you have a sword, get rid of your second weapon before the second chapter of a level. The sword will have the highest possible ammunition level when the action starts up again.
"Halo 3" Cheats
While playing "Halo 3," you can unlock special awards and gamer points by accomplishing tasks. To unlock the "Campaign Complete: Normal" award and 125 points, you must beat the entire game on the Normal difficulty setting. You get the "Guerrilla" award and 10 points by accumulating at least 15,000 points during the first meta-mission. If you kill at least 10 consecutive enemies in an online ranked match without being killed, you get the "Killing Frenzy" award and five points. Once you find at least five grenade sticks in an online competition, you get the "Lee R. Wilson Memorial" award and five points.