Brute Force

All mission maps:
Create a new profile, name it VENGAR, and start a new game. A message will appear to confirm correct code entry. All of the missions in the game will be unlocked and available at the start.
Jax1299.

Stronger characters:
Create a new profile, name it MATTSOELL, and start a new game. A message will appear to confirm correct code entry. When playing under this file, Tex and Brutus can take more than three direct shots of the rocket launcher without being near death. Note: "MATTSOELL" is the project director for Bungie who made Halo. Note: You must watch the full ending once, have all the DNA canisters, and at least one open campaign file for this code to activate.
Jax1299.

All characters:
Create a new profile, name it GARNER, and start a new game. A message will appear to confirm correct code entry. All single and multi-player mode characters will be unlocked.
Jax1299.

Brutus' special changes:
Create a new profile, name it GARNERVEN, and start a new game. A message will appear to confirm correct code entry. Brutus' special meter will last longer, and attacks be more powerful. Note: You must watch the full ending once, have all the DNA canisters, and at least one open campaign file for this code to activate.
Jax1299.

Brutus' appearance changes:
Create a new profile, name it GARVEN, and start a new game. A message will appear to confirm correct code entry. Brutus' character will look completely different, and he is several times as powerful as before. Note: You must watch the full ending once, have all the DNA canisters, and at least one open campaign file for this code to activate.
Jax1299.

Rapid fire weapons:
Create a new profile, name it RAPIDFIRE, and start a new game. A message will appear to confirm correct code entry. All weapons, even the shotgun, will fire at a higher rate of speed. Note: Ammunition is eaten up much faster. Note: You must watch the full ending once, have all the DNA canisters, and at least one open campaign file for this code to activate.
Jax1299.

Dumber enemies:
Create a new profile, name it SPRAGNT, and start a new game. A message will appear to confirm correct code entry. Even under the Brutal difficulty setting, enemies will miss you more often, act stupid, and your squad will be more intelligent and shoot and kill enemies with no instructions. Note: You must watch the full ending once, have all the DNA canisters, and at least one open campaign file for this code to activate.
Jax1299.

Better aim:
Create a new profile, name it DEADAIM, and start a new game. A message will appear to confirm correct code entry. You will notice your teammates aim and hit things much more often. Flint's special meter will decrease slower, and she will drop enemies quickly. Note: You must watch the full ending once, have all the DNA canisters, and at least one open campaign file for this code to activate.
Jax1299.

Higher defense:
Create a new profile, name it ERINROBERTS, and start a new game. A message will appear to confirm correct code entry. This somewhat increases your squad's defense in damage taken. They will not get hurt as often, but also seem to dodge projectiles. Note: You must watch the full ending once, have all the DNA canisters, and at least one open campaign file for this code to activate.
Jax1299.

Quicker death:
Create a new profile, name it DBLDAY, and start a new game. A message will appear to confirm correct code entry. Everyone will be easier to kill; your squad may also die much faster. Note: You must watch the full ending once, have all the DNA canisters, and at least one open campaign file for this code to activate.
Jax1299.

Cartoon mode:
Create a new profile, name it HVYMTL, and start a new game. A message will appear to confirm correct code entry. During the game, everything looks like a cartoon, with coloring book-style models, blood resembling paint, lava with a paper feel, and different level layouts. Note: Note: You must watch the full ending once, have all the DNA canisters, and at least one open campaign file for this code to activate.
Jax1299.

Tougher game:
Create a new profile, name it BRUTAL, and start a new game. A message will appear to confirm correct code entry. This code completely beefs up the enemy AI and seems to change their behaviors. Even under the Standard difficulty setting they will ambush you, find a way to hunt you, and come flailing out in order to kill you. They will take the same amount of hits, but be much harder to put down, thus making the entire game harder. They drag themselves away when wounded, similarly to the original previews of the game or when you fight the Halo aliens under the Legendary difficulty setting. Note: You must watch the full ending once, have all the DNA canisters, and at least one open campaign file for this code to activate.
Jax1299.

Bots in multi-player:
Start a game of Squad Deathmatch. Plug in controller two and set the A.I to "Fire At Will". Go around and pick them up some good weapons and medkits, then disconnect the controller. Your squad will now be facing three heavy thinking bots in multiplayer mode.
Jax1299.

Bonus multi-player characters:
Get the hidden DNA containers to unlock various characters in multi-player mode.
GAMEPLANET18.

Confed Marine: Mission 1 or Mission 6
Feral Colonist: Mission 2
Feral Outcast: Mission 3
Feral Shaman: Mission 9
Fire Hound: Mission 13
Gunthar Ghent: Mission 10
Hunter Lord: Mission 18
McTavish: Mission 14
Militia: Mission 5 or Mission 11
Outcast Shaman: Mission 7
Seer Follower: Mission 4
Seer Priest: Mission 8
Shadoon: Mission 12
Shrike Heavy: Mission 16
Shrike Hound: Mission 17
Shrike Soldier: Mission 15

Hint: Keep items:
If you lose your life in single player mode, join the game using controllers two, three, and four to get them back.

Hint: Maximum MK ASLT ammunition:
When you find a duplicate MK ASLT, keep picking it up. It will raise your maximum ammunition to 600.

Hint: Regain special faster:
When your special gets low or runs out, find a place to hide then click the Left Analog-stick to duck or squat. Your special will increase three times faster when compared to if you were standing.
Corey A Barnes.

Hint: Respawning teammates:
When one of your teammates die, you can respawn them instantly by simply plugging in another controller, hitting Start, choosing the desired character, then quitting with that person. This will make your character under A.I. control, allowing him to keep fighting.
Rambo Force.

Hint: Defeating the final Boss:
Use Hawk to go to the farthest yellow map marker and take everything out (enemies, turrets, and force field). Activate the console. After the door opens go to the room with the turret and destroy it. Activate the console then go out and through the door that opened. This will lead you to the second yellow dot, but stay out of the Boss' line of sight. Take Brutus up to where the farthest yellow dot is located. Use Vengar or you will probably get killed. Use Tex as desired, as he is not essential for this battle. Finally, use Flint to snipe the Boss, who should be distracted by Brutus who just ran to the opposite end of the map. Shoot him in the back until he warps to the place where he powers up (where the Blue Power Orb was located before it was destroyed). Take Hawk to the command console and activate it (the closer yellow map dot).

Hint: The Anvil: Hunter Lord's DNA:
Send Hawk in invisible mode to avoid getting hurt. Go to the far right side in the beginning. There is a small ledge. Climb it until you reach a fork in the road. Go to the one with fog to the right. Keep going and stay low. At the dead end, you will see a high cliff that drops off into a pit of acid. There will be a tube hanging out. Very carefully climb out on it until you see a tiny ledge off to the right side. Jump on it and climb to the top. There will be a flat piece of land, and the DNA will be up there.
FroBoy427.

Before doing anything, send someone like Hawk to distract him. When starting, go to the right and there will be a small ledge. Climb it until you see a split in the path. Take the one with the fog on it. Then, go to where you can see the recharging station. There is a short pipe at the end of the trail. Go on it, but be careful not to fall off the left side. Then, jump onto a small ramp on the right side. Next, go to the top of the ramp to find the DNA.
FroBoy427.

Hint: Cemetery Gates: Feral Outcast's DNA:
Just before you enter the foggy part and need Brutus, there should be a tower on the left side. To reach it, kill the mutant. Go inside the tower and you will find Feral Outcast's DNA.
Sabatino Scardetta.

Hint: Cemetery Gates: Early Sweeper V:
At the beginning when the Captain says "Don't shoot the barrels...", shoot the giant barrel to the northeast. This will kill most of the mutants. Then, go to the giant station. Go up the stairs and kill the mutant. The Sweeper V is in fornt of the yellow thing, with 8 shots. You will find ammunition with brutus' Venger later in the level.
Sabatino Scardetta.

Hint: Cemetery Gates: Hidden mini-gun:
After you see the bones, kill the mutants. Do not turn; just go straight. You should go into a hole. There will be ammunition for the gun; or if you ran out of ammunition throw the gun away. There is a fresh one with full ammunition.
Sabatino Scardetta.

Hint: Kill Shadoon: Defeating Shadoon:
Before doing this, do not take out the Wall Of Souls in the last chapter in the mission. Leave this up so that Shadoon can not go after you. After deafeating Shadoon in the temple room, have everyone set to cover the character that you are controlling. Warp out to the main cavern. As soon as you are warped out, run to the tunnel to the right (that lets you get past the Wall Of Souls that is still up). Once in the tunnel, quickly tell all your squad member to run to the tunnel using the Move To feature. Keep running until you are at the top of the tunnel. Then, once again tell all your squad to move to the top of the tunnel. Place Tex and Brutus on each side of the tunnel entrance, just slightly into the tunnel. Put Hawk and Flint at the entrance of the tunnel. Have Flint out enough to where she can see the hut near where the squad warped out. Shadoon and the Fire Hounds will come up the tunnel. This will make it very easy to ambush them. Shadoon does not warp away as quickly when grenades are thrown at him.
Mufaza.

Hint: Kill Shadoon: Shadoon's DNA:
To get the DNA of Shadoon, walk over his body after you kill him.
Madmad16.

Hint: Hostile Reception: Explore asteroid:
When leaving the last tunnel and returning to the outside, notice the turret located on the tunnel you just exited. Face the tunnel and walk to the right side of it. Follow the rocks to where the rock wall meets up with the tunnel's outer surface. You will fall through a small gap in the asteroid. It may appear you are stuck; just "wiggle" slightly. From here, you can walk around the asteroid and revisit some tunnels.
The Smiling Lord.

Hint: Shantytown: Pipe ambush:
This is an ambush secret in the Deathmatch level Shantytown. When you get to the bridge, look over to your left to see a lot of ruins and sheds. Walk along the left wall to the fallen tower building. Take your character through the hole on the far right-hand side. With a few jumps, you can get someone like Flint to the right-hand side of the pillar. Behind here is a group of pipes. Go towards them and jump on the rock to get all the way inside the top pipe. Leave Flint or a Fire Hound here. When the squad comes up the bridge, you can let your other teammates stand their ground and pick them off with ease from inside the pipe. Your human or CPU opponents will not catch on until it is too late.
Jax1299.

Hint: Shrike Rogue: Shtrike Hound's DNA:
Go to the temple which has the alien technology. After you get the alien thing, go to the top of the temple. Walk around the top part of it. You should find a broken down wall. Jump inside of it. When you land on the ground, you should find Shrike Hound's DNA.
Sabatino Scardetta.

Hint: Dog ambush:
Notice that the hounds can take a lot more damage when in the lava or toxic pools. There is a good reason for this. If you stock up on a few medkits and let the hounds stay under the hazard, they can hide there when the squad runs out. They can then leap out of it like fishes and ambush them before going under to hide again. This is a great tactic for the Abaddon and Shantytown levels.
Jax1299.

Hint: Soda cans:
In some levels, such as Seti 2049 you can find soda pop cans lining the tables where the guards man the outposts. If you Hawk over there and shoot them with a pistol, they will start running around wondering where the noise is coming from. If you are Hawk, keep her cloaked and plant a group of Sentry Bombs in the same area that the guards usually patrol. Shoot the soda cans then run and hide. No more than a second later, you should hear all of them explode after accidentally trampling on the mines while looking for you.
Jax1299.

Hint: Brutus:
For all enemies except the last Boss, use Brutus to charge the enemy. He only losses his Vengar when the enemy is dead. You can charge them and damage them multiple times, which is very effective.

Use Brutus' specialty to find snipers before they find you. Just flick it on and off.
Death Summoner.

When playing as Brutus and you run out of medkits, use Venger in a corner with no enemies nearby. When you run out, crouch. Your special will regenerate faster. Repeat this until your health is full.
cwzy-azn-guy.

Hint: Flint:
If one of your characters dies, notice that they have red blood surrounding them. However, whenever Flint dies, there will not be any blood, only a black spot from the gun debris and ash. She will not have any blood because she is a robot or a sentry, as she mentioned earlier in the game. A good way to see this is to go directly to squad fight. Do a Brute Force against another Brute Force team. Have one of the team's Flint sniper all of its teammate's characters except for one. To save time, aim for the head. Then, have the other character who you left standing shoot Flint and kill her. If you keep shooting her body while its on the ground, it will not bleed.
Neo Dragon.

Hint: Flint: Quick spotting:
When you enter a large area, flick the special on and off to quickly see if there are any moving targets. If there are moving targets, zoom in and kill them.
Warskier.

Hint: Hawk:
If you do not have anyone you can play with and you are forced to do this yourself, you can have a relatively easier time (and save ammunition) by simply using Hawk (the Assassin) to kill one or two enemies while cloaked. Then, retreat to regenerate energy. Repeat this until you need the really heavy firepower of your AI companions.
GAMEPLANET18.

While playing as Hawk, select your PowerBlade "PwrBld" in your inventory. Use her specialty (cloaking) and stab as many enemies as you can. One stab in an enemy kills them, and since Hawk runs very fast, you can take out many enemies without taking any damage.
Geoff987.

Hawk is a very good character, but you have to use her correctly. When Hawk is in stealth mode and shoots, her special decreases a lot faster. If you kill about three aliens this way, she will have no stealth remaining, and she will be nearly helpless as she has very little health and special. The proper way to use her is to scout. Put Tex, Brutus, and Flint in stand by mode so they do not follow, then scout an area in stealth mode. You can also try stealing ammunition. Then, run back to Brutus, Tex, and Flint. The stealth mode lasts a short period of time. When you use it, be very quick as she is valuable.
warskier.

When Hawk is invisible, you can sneak up behind enemies, turn off invisibility, then kill them. Turn her invisibility back on quickly. You must do this when there are no enemies around or if none of them are looking.
Crashburn102.

Hint: Tex:
When you select a character, notice that some of them have larger health and special meters. When you select a difficult level, unless you charge up Hawk's stealth meter, you should choose Tex. He has the largest health/special meters.
xruby722.

Enable the "Rapid fire" code and get two miniguns. Take out both guns and Tex will be almost invincible.
Froboy427.

Hint: Getting rid of mines:
If you are behind four mines and do not want to shoot or disarm all of them, throw a grenade in the middle and they will all explode.
FroBoy427.

Hint: General tips:
Make sure to tell the other characters to support you when attacking a frag.
BFerrer.

When in combat, tell your teammates to fire at will, move around a lot, and throw grenades when there are a lot of aliens grouped together.
Greenbay211.

Always pair one guy with one girl when playing regularly.

To clear out a lot of enemies, have Tex and Brutus go in and do as much damage as possible. Then, retreat back to Flint and Hawk. Also have Flint give you sniper support and have Hawk cover Flint. It also helps to send Hawk in invisible to scout and kill as much as possible.

When going into any hallway or cave, keep Flint back, but able to snipe clearly into the hall or cave. Put Brutus on one side and Tex on the other outside of the hallway. Have Hawk explore, and if needed lead the enemies out. They will be blown away from front, left, and right and from Hawk.

Glitch: Dead character's speak:
On some missions, dead members will talk. For example, on Chapter 2 of The Anvil, Tex talks about the dead man on the spike. However, if Tex is dead, you will still hear his voice.
HyPNoTyK.