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- 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.
- 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.
- 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.
- 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 headshot, 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. This skull causes you to go back to the last checkpoint when you die in co-op mode.
- 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.
- 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". This skull makes enemies fire at a faster rate.
- Famine Skull
After you get off of the slowly decending elevator in "The Oracle", you will come to a hallway where you see a handful of dead bodies. Continue into the next room, and you will be on the second floor of a room that has windows. When you enter this room, look to the right, and find the third pane of glass. It should be to the right of a wall that has some flood guts splattered on it. Shoot out this window, and either window directly across the room. If you look below you will see a platform that has four tall posts. On the far side of the room there is a column that is right in between the two windows, on the far side of the room. Turn on your active camo, and jump to the center platform. Jump on either of the posts on the far side of the platform and jump to the column between the windows. Make another jump through the window you shot out and make a left. Walk all the way to the end and you'll find four flood elites convulsing on the floor, with the Famine skull in the middle of them. When you have this skull all weapons will have less ammo.
- Mythic Mode
In "Sacred Icon" there is a semi outdoor area which has the same type of area right next to it. There is a large sentinal in front of each one. Go past this area and down the piston and you'll be in a vary dark and dank flood infested area. There's a stack of 6 or 7 boxes as you enter the room. Use them to jump up to the landing above. There are a handful of alcoves on your right hand side. The skull is in the third alcove, floating above a dead human flood.
* Sputnik Mode
At the start of "Quarantine Zone" on Legendary difficulty turn directly around, and you should see a tunnel. Head down the tunnel and go straight until you exit it. Go straight across the open area, and you'll come across a broken pipe tunnel on your right. Straight in front of you is a small ledge running across the wall, above the green pit. Carefully get onto that small ledge and walk all the way to the end of the ledge to find the Sputnik skull. In this mode explosion force and melee force is greater.
* Unknown Skull
At the begining "Armory" wait in the room until the Sarge starts telling you to get into the elevator. You MUST wait for him to say "Would it help if I said please?" When he says this, get into the elevator and go down to the tram. Get on the tram and face towards the INSIDE of the building. Press up against the glass doors towards the inside of the building. You should hold 'X' down, and you should pick up the skull. It's on a stack of green crates, near the end of the tram ride. * Thunderstorm Mode
On the level "Cario Station" on legendary, make your way to the "Priority Shift" checkpoint. Progress until the room with mounted plasma turrets, right after the armory with the Elites. Clear out this room, and get on the raised area with the plasma turret that is on the side of the wall where the window curves. Look for two parallel beams on the ledge above. Climb up the supports for these beams and crouch jump up onto the upper ledge, then onto the beams themselves. Walk in the direction you came from and there will be a small ledge sticking out to the left, jump on it and pick up the Thunderstorm Skull from inside the trash container. This turns all Covenants into their spec ops rank. * Midship bunny
On the level Midship, go to the top where the sword spawns. Now walk to the doorway which doesnt have a big roof. Look up and you should see an outline of a bunny! * Why am I here? Message in Beaver Creek
This easter egg is very simple. Go to beaver creek. Run to where the sniper rifle spawns. Jump up on to the ledge in front of you and push all of the rocks down. When you push the big rock down loook at the wall that was behind of it. If you look carefully, you should see "Why am I here?" Scratched in to the wall. (Note: if you can not see it then back away from the wall some and it should look much clearer.) * Sign on Zanzibar
On the beach on Zanzibar, you will see signs that say NO SWIMMING. Well, go to your xbox dashboard, go to the Settings, Clock, and change every number you can to 7 , then pop Halo 2 back into your xbox and load it up. WARNING: Do not sign into XBoxLive, it resets your clock. Now go to Split-Screen and start a game on Zanzibar. Go to the beach and look at the sign, it will mention something is missing, and there is a bloody dog's head. * Rex-In outskirts
First start going torwards the blind skull way but when you go up there take a left instead of a right and jump on the ledge, then crouch jump on top of another ledge (which would be right above the wreckage) then jump on the ledge across the wreckage then continue the pathway intill you reach the area with the sword sticking out of the ground (It's inside a broken rooftop), right next to it is a rock with the word REX written on it. * Giant Soccer Ball
It's on the level "Metropolis" on any difficulty I do believe. Use the same method to get a Banshee through the tunnels as you would if you were getting the Scarab Gun. (See the corresponding cheat for more details)
Now take your Banshee away from that half-dome thing and fly through the level using the same path you would as if you were walking. Once you get to the highway where the Warthogs are fighting the Ghosts, keep flying straight toward the half-demolished building. Fly into it and go to the bottom level. Behold! A giant soccer ball! It's great fun to mess around with, especially if you have the Scarab gun. * Zanibar Computer Screen
On Zanzibar, after you open the gate the computer screen (used to open the gate) changes. When you zoom in on the words you can read how to fix your computer and some other gags * Messages on the bomb
If you play multiplayer and hide with the bomb, then you probably have noticed this already. If you stand somewhere long enough, the mastercheif will start to toss the bomb up and catch it. Eventually he will examine the bomb, and you can read what it says on the bottom. One message is "goodbye" and another is "xoxoxoxo". * The Face of Chris
On the map Containment, get a sniper rifle and go anywhere where you can see the part of the Halo in the sky that's closest to the Sun Base (the base with orange-yellow glowing buildings). Zoom in with the sniper on the part of the halo that's just below where it begins to get dark. In the clouds you should be able to see the face of Chris Carney (grinning happily), one of Bungie's developers. * Weird Window Reflections on Headlong
In Headlong, grab a banshee and fly to the part of the level with water. On the same side as the Warthogs spawn, almost at the end of the level itself, there are some windows. Look closely at them, they aren't reflecting the other side of the level, but showing concept art for Halo 2. (A would-be human city at night)