Unlockables

Multiplayer Map- Foundation via Xbox Live
Bungie has decided to give the multiplayer map to anyone who signs on via Xbox Live. You will be prompted with an update as soon as you try to sign on. The update will unlock the map, improve support for 480p resolution display's, and speed up wait times in matchmaking.
Unlockable Map
Unlockable-How to Unlock
Multiplayer Map Foundation-Beat the singleplayer campaign on any difficulty, performing at least one undone tutorial move on the last level. Also, you can get this map through an automatic Xbox Live update.

						Easter Eggs
"Blue Screen of Death" in Zanzibar:
In the multiplayer map Zanzibar, there should be a computer on the upper level on the defense side that opens up the main gate into the base. After you activate this, the screen goes blue with the infamous BSOD.
Angry Mode:
When you are the Master Chief trying to recover the index from the Prophet of Truth on the Covenant Holy City go until you reach the first outdoor area with dirt and vegetation. Take a right as you enter this room and run up to the wall past the gravity lift that leads up to the sniper point. Get on top of the wall by going up the dirt mound on your left. Follow the wall until you reach the floating skull called "Angry".
Assassins Mode:
A skull similar to the one that activates blind mode can be found if you Start on "regret". After the first lift ride (before the first underwater elevator), grenade jump from the front awning of the lift to the ledge in front of you (the one with two turrets).
Grenade jump AGAIN onto the next ledge.
Make your way to the back of the building. On Easy, you'll only find the skull. On Legendary, however, 2 invisible Elites carrying swords just shake their heads wildly, ignoring you completely.
Black Eye Mode:
In the level "The Great Journey"
It is on top of the contol room where Johnson blows up the door.
Shield won't regenarate if picked up.
Blind Mode:
At the beginning of Outskirts jump on top of the light on top of the door with a crouch jump, then jump to the left platform. Turn to your left and go down the long dark corridor and pick up the skull; it will say blind and your screen will flash black for a while. In this mode you can not see your weapon, body, shields, ammo, or radar. To get rid of this feature use the following method: 1. Turn off your XBOX or Save and Quit. 2. Go to Campaign and select level and choose Cairo Station. 3. Skip the cinematics and then Save and Quit. 4. Go Outskirt and your hud is back.
Catch Mode:
Right after u get out of the sewers (Tunnel), there is a big area and 2 ghosts, kill every thing first, then go to the middle of it where u see a arc that leads up onto a building, throw a grenade down and jump by it to get enough height to start climbing it. When you get to the top take a left and hug the wall around the structure and the skull will be there.
It says Catch
Envy Mode:
On the level "Delta Halo" on Legendary Difficulty, Progress until you reach the area during the "Push through the covenant held ruins" where you have to clear a Landing Zone for the Pelican to drop weapons. You will know you are in the right area when cortana says "they're pouring out of the center building". Anyway that area has Plasma turrets along its borders. A little bit after the left side turret you will see the outline of a door in a wall, but the door has a solid rock slab in it and a rock in front of it. Jump on the rock then jump to the ledge above the door then jump on the ledge to the left. Now jump onto the building with the sealed door using grenades. Atop the building you will find two dancing elites and the "Envy Skull". Pick up the envy skull and you will be able to use Active Camoflage like the Arbiter.
Grunts Birthday Party Mode:
In the level Arbiter on Legendary. Once you get to the first banshee section, fly immediately straight down all the way to the bottom of the map. In one of the cracks where the large cylinders connect to the station. There will be a circle of grunts dancing around a skull. When you pick up the skull; it will say Grunt Birthday Party on the screen. Now when you kill a enemy with a projectile weapon, they will blow up like a plasma grenade was stuck to them.
To get rid of this feature use the same method as the blind mode.
Iron Mode:
On the last Master Chief Level, on Legendary Difficulty, when you enter the final Gravity Lift, look up. A skull will pass through you extemely quickly so you must start holding X a bit before you actually pass it to grab hold of it. Once you grab the Iron Skull, Iron Mode will be activated.
Mini - Master Chief action figure:
In Delta Halo, when you get to that "staircased" waterfall that you must climb up, then jump onto what appears to be a sniper rifle case, then a quick jump to land - as you turn that bend past that cave where the covenant snipers were - head into that cave - it is a dead end... Take a look at the floor - with a scoping weapon... A golden mini - Chief action fugure will be there. If you shoot it, it will also bleed.
Posters at the Old Mambassa Crash landing *after Cairo*:
After you crash land on Old Mambassa, you can see posters all around with the Master Chief from the demo and some grunt posters.
Thunderstorm Mode:
In the large room after the armory, you need to use a duck-jump to get onto a light fixture on the right wall (right of the room when you enter) and then jump from there onto the higher area. There is a series of diagonal beams. Walk up one near to the end of it and use it to duck-jump onto one of the rails. You can fall between the rails, so be careful. Once on the rail, walk down it until you can jump onto the highest platform. Then bash the trashcan.
It says Thunderstorm when you pick it up.
	
					Glitches
Give your squadmates better weapons:
Once you have almost used up your sniper rifle, beam rifle, or rocket launcher (with 1 shot left ), trade with your squadmate. Once they have that weapon, they have limitless ammo for it and can help you out immensely with the more powerful weapons. There are two points to note: if you try and trade your weapon back from them, it will still have the same amount of ammo that it had when you gave it to them and the energy sword cannot be traded with human squadmates.
Skip tough Brute battle before the end boss:
When you are flying around in the Banshee during the final level when you are giving support to your ally. You can skip directly to the final boss sequence if you are still in the Banshee after te door gets blown open. Fly to the right of the control centre building and aim towards the bottom right and if you fly close enough you should get a white screen indicating that you have started the cutscene. When it's over you will be at the final boss without fighting your way to him.

					Secrets
Beat Tautarus easily:
When you first start the fight, make sure Tautarus' attention is on another NPC and not you. Grab the energy sword from one of the bodies lying around and wait for his back to face you. When he does, dash behind his back and rapidly tap R, It will hurt him and not allow him to react and attack you. About 30 seconds of this kills him.