The following cheats can be used without being in debug mode, but requires you to achieve a certain goal in each mission. It also must be done under the realistic or director's cut difficulty setting:
Alien Episode I - Temple Cheat: Sniper Munch. Objective: Ten live civilian head bites. Alien only. It allows you to do long distance head-bite attacks (a ranged weapon for the Alien). The best way to get this cheat is make sure the civilians throw their Molotov cocktails away first and do not hit themselves, then wait for them to cower and pick them off. Do not forget the ones locked in the cages.
Alien Episode II - Escape Cheat: Nausea. Objective: Complete the level in under two minutes. The entire screen waves around and will probably give you motion sickness before too long.
Alien Episode III - Ferarco Cheat: Pipecleaner. Objective: Fifteen dead civilian head-bites. It is not just stick figures but actual pipe cleaners wrapped around for enemies. Note: Kill them using your tail and not your claws, or you risk hacking their head off.
Alien Episode IV - Gateway Cheat: Motion Blur. Objective: Complete the level in under four minutes with an average speed of more than nine meters-per-second. Motion blur makes everything that moves blurry. To get it, learn the level and run.
Alien Episode V - Earthbound Cheat: Mirror. Objective: One live Predator head-bite. This makes the level mirrored left to right.
Colonial Marine Episode I - Derelict Cheat: John Woo Mode. Objective: 80% head shots. Have 80% of your hits as head shots, or 80% of your kills by removing the head.
Colonial Marine Episode II - Colony Cheat: Grenade. Objective: 40% accuracy. You start the game with 99 grenades in your pulse rifle, no bullets, and cannot pick up any other gun except pulse rifles to add to your grenades.
Colonial Marine Episode III - Invasion Cheat: Warp Speed. Objective: Finish in under four minutes. You need to know the level and have a little luck.
Colonial Marine Episode IV - Orbital Cheat: Land of the Giants. Objective: Less than twenty shots. Makes you very tiny, but just as deadly and perform about as well.
Colonial Marine Episode V - Tyrargo Cheat: Slug Trail. Objective: 32 Alien kills. All Alien enemies start with a missing leg. They crawl around bleeding a trail behind them.
Predator Episode I - Waterfall Cheat: Pigsticking. Objective: 80% accuracy. The speargun has infinite ammunition and shoots about a dozen or so spears at a time in a shotgun-like spread.
Predator Episode II - Area 52 Cheat: Super Gore. Objective: 25 Colonial Marine trophies. Makes kills much more bloody.
Predator Episode III - Vaults Cheat: Disco Inferno. Objective: Complete the level with under 100% damage. All the walls will glow in bright multi-colored patterns.
Predator Episode IV - Fury 161 Cheat: Balls of Fire. Objective: 40 Alien kills. Your enemies are made out of flames (useful for seeing them in the dark). Take your time in the first part of the level. Explore and kill all Aliens you see.
Predator Episode V - Caverns Cheat: Rainbow Blood. Objective: Spotted less than 15 times. The cheat makes the blood, lights, smoke, etc., constantly change in a rainbow of colors.
Alien Bonus II - Derelict Cheat: Impossible Mission. Objective: 20 live Colonial Marine head-bites. You take more damage.
Colonial Marine Bonus I - Temple Cheat: Free Fall. Objective: Complete the level with under 100% damage. Makes the level spin out of control. It does not spin quickly -- it only causes gravity to be variable. A wall could be a floor from one minute to the next. The Alien will suffer the least so long as he keeps clinging to the walls, and the Predator will not be hurt by long drops.
Colonial Marine Bonus II - Vaults Cheat: Under Water. Objective: Complete the level with under 60% damage. It makes things a little wavy, adds a bluish tint, and makes you fall slower.
Predator Bonus I - Invasion Cheat: Ticker Tape. Objective: 15 Alien trophies. Makes Alien enemies have a trail (like the Predator's disc). Can only be used by a Marine and Predator, and only on levels with Aliens. Aliens tend to explode when killed, and their bodies melt away in seconds. There are only seventeen aliens in the entire level. You have almost no margin of error. Take them on one at a time, shooting them at their feet with your pistol. Once they go down, take out your wristblades and bag the trophy.
Predator Bonus II - Escape Cheat: TripTastic. Objec: 10 Civilian trophies. Makes everything on the screen transparent, wavy, and change colors like a rainbow.