If you beat the game on Legendary mode, you will get a special, extended ending. Keep in mind that you only have to beat the final stage on Legendary mode, and not necessarily the rest of the game, in order to unlock this ending.
Unlockable: Elite Armor Permutations
Unlock the following Elite armor permutations by fulfilling the requirement listed…
- Ascetic (Body) – Get the Up Close and Personal Achievement
- Ascetic (Head) – Get the Steppin’ Razor Achievement
- Ascetic (Shoulders) – Get the Overkill Achievement
- Commando (Body) – Get the Triple Kill Achievement
- Commando (Head) – Get the Overkill Achievement
- Commando (Shoulders) – Get the Killing Frenzy Achivement
- Flight (Body) – Complete Tsavo Highway (on Heroic or Legendary)
- Flight (Head) – Complete the campaign mode (on Legendary or Heroic)
- Flight (Shoulders) – Complete The Ark (on Heroic or Legendary)
Unlock the following Spartan armor permutations by fulfilling the requirement listed…
- EOD (Body) – Complete Tsavo Highway (on Legendary)
- EOD (Head) – Complete the campaign mode (on Legendary)
- EOD (Shoulders) – Complete The Ark (on Legendary)
- EVA (Body) – Complete Tsavo Highway (on Normal, Heroic, or Legendary)
- EVA (Head) – Complete the campaign mode (on Normal)
- EVA (Shoulders) – Complete The Ark (on Normal, Heroic, or Legendary)
- Mark V (Head) – Get the UNSC Spartan Achievement
- ODST (Head) – Get the Spartan Graduate Achievement
- Rogue (Head) – Get the Spartan Officer Achievement
- Scout (Body) – Get the Too Close to the Sun Achievement
- Scout (Head) – Get the Used Car Salesman Achievement
- Scout (Shoulders) – Get the We’re in for Some Chop Achievement
- Security (Head) – Get 1,000 Gamerscore Points
- Security (Shoulders) – Get 750 Gamerscore Points
Blind (Located: Sierra 117)
The arms of the player and the motion tracker disappear.
Cowbell (Located: The Ark)
Your explosives increase in strength.
Grunt Birthday Party (Located: Crow’s Nest)
If you manage to get a headshot on a Grunt, the Grunt will explode.
I Would Have Been Your Daddy (Located: The Covenant)
Unlocks new dialogue for the campaign.
Black Eye (Located: Crow’s Nest)
When activated, you will have to battle enemies with melee tactics to regain shield energy.
Catch (Located: The Storm)
When activated, enemies will throw more grenades.
Famine (Located: The Ark)
When activated, dropped weapons will hold less ammunition.
Fog (Located: Floodgate)
When activated, the motion tracker disappears.
Iron (Located: Sierra 117)
When activated, you will be sent back to the beginning of the stage you’re on when you die instead of to the last checkpoint.
Mythic (Located: Halo)
When activated, all enemies will have twice as much health.
Thunderstorm (Located: The Covenant)
When activated, enemies will be of a higher rank.
Tilt (Located: Cortana)
When activated, enemies will become more resilient to your attacks.
Tough Luck (Located: Tsavo Highway)
When activated, enemies are skilled at getting away from projectiles such as grenades.
To unlock the Katana, which is a non-usable item that is essentially the fourth piece of Hayabusa Armor, get all thirteen Skulls in the game, and achieve a gamerscore of 1,000 (complete all achievements).
While collecting skulls, keep in mind that you have to start the stage from the beginning (not from a checkpoint), but once you acquire the skull you’re seeking, you can save and quit at any time without finishing the stage. This will allow you to collect skulls without having to worry about finishing the stage successfully.
You will unlock a secret achievement by finding all seven terminals listed below…
Terminals: The Ark
Go left through a door once in the very first building of the stage. The terminal is located beyond a curving passage.
A terminal is located right near the device that activates the bridge on this stage.
There’s a secret room in the third building which holds the third and final terminal on The Ark. After you come across and kill a group of sleeping Covenant enemies, head down the nearby corridor. You’ll reach a door that is locked if you do. To the left of the locked door is an open door. Head through the door, and then turn around to find the terminal.
Terminals: The Covenant
Head to the stage’s first tower and stand on the elevator. Face the control panel, and then turn left. Jump over the obstacle, and find the terminal you seek.
Head to the stage’s second tower and walk towards the entrance. When you come across a locked door, turn around to find the second of three terminals here.
Head to the stage’s third tower and stand on the elevator. Face the control panel, and then turn right. Jump over the obstacle, and find the third and final terminal on the stage.
Traverse the first cave, and then head right until you come across a building. Walk along the passageway towards the building. Once inside, run left to find the terminal.
Having trouble with a Scarab? Or maybe you don’t want to get on board (and abandon your bright, shiny Scorpion). Try this strategy instead: on the back of every Scarab, there is a circular glowing spot you can shoot to do damage (it is similar to the glowing spot on the back of Wraiths).
Locate the spot on the Scarab’s rear armor that is below its rotating anti-air “ass” (or abdomen) turret. A few shots from Hornet missiles or Scorpion tank shells and the armor will fall off and reveal the critical system you normally need to board to wreck. Don’t forget that shooting the Scarab’s legs will stop it from turning.
If you don’t have an Energy Drainer item, the plasma pistol’s charged shot can be used to stop vehicles (but doesn’t stop vehicle mounted weapons). Pack a plasma pistol when there are vehicles around; it’s the next best thing to a rocket launcher.
The custom power-up you can add in the Forge will greatly make or break your game (depending on how many you put in your map and how fast they respawn). Since you can only adjust the custom power-up just before a match, be sure to jot down what effects you are looking for in a custom game.
Custom power-ups can only be used in Custom Games. Press BLUE to edit the match options in a Custom Game. Go into Weapons and Vehicles, then locate the Custom Power-up Traits. Have fun!
On the second level of the campaign, when you’re escorting characters to their ships, you can head the wrong away from where you’re supposed to go to complete your mission. If you do, you’ll run into two characters (separated by a door) having a humorous conversation.
On the Sierra 117 mission, the Pelicans will crash. After that, you should clear the area like you normall would. As the area narrows as you proceed, there are some rocks on your left that you can jump on. Continue along a ledge thereafter. Once it heads down, you’ll pass a large boulder on your left. After you do, turn around and take a look where the wall and the boulder intersect. You’ll see a family of primitive cavemen-like people!
When you beat the game, you will be shown a memorial for the men and women that died in-game. Spartan 117 is one of those considered KIA, but if you wait for the credits to end at the end of the game, you will see that Spartan 117 is very much alive (this only applies if the game is finished on any difficulty but Easy).
Easter Egg: Elephant Flipper
In the Forge, edit the Sandtrap map and create a Scorpion. You can use the tank to lift and flip the Elephant (the large Sandcrawler vehicle). Once the Elephant is upside down (or undrivable), approach it to flip the vehicle and get a humorous message.