Full list of all 86 Halo 4 achievements worth 2,000 gamerscore. It takes around 25-30 hours to unlock all of the achievements in the base game on Xbox 360.
The base game contains 49 achievements worth 1,000 Gamerscore, and there are 5 DLC packs containing 37 achievements worth 1,000 Gamerscore.
Completed the Campaign cooperatively on Heroic or harder.
Completed 25 Challenges.
Completed all chapters in any 5 episodes of Spartan Ops on any difficulty.
Completed all chapters in Spartan Ops Episode 1 on Legendary difficulty.
Assassinated a Knight in any Spartan Ops mission.
Completed a Spartan Ops chapter solo on Legendary.
Completed the Campaign on Heroic or harder.
Completed the Campaign on Legendary difficulty.
Completed any Campaign mission with 3 or more Skulls on Heroic or harder.
Completed any Campaign mission cooperatively on Heroic or harder.
Won 20 War Games matchmaking matches.
Uploaded a File to your File Share.
Saved a Screenshot from the Theater.
Saved a Film Clip from the Theater.
Completed the Campaign on Normal or harder.
Completed mission 8 on any difficulty.
Found all of the Terminals in the Campaign.
Completed mission 7 on any difficulty.
Ranked up your Spartan-IV to SR-20.
Won 5 War Games matchmaking matches.
Changed your Spartan's pose in the Spartan ID card.
Completed mission 6 on any difficulty.
Completed mission 5 on any difficulty.
Changed your Spartan's armor in the Spartan Armor card.
Completed mission 4 on any difficulty.
Completed mission 3 on any difficulty.
Completed mission 2 on any difficulty.
Found a Terminal in the Campaign.
Created and saved a Custom Map in Forge.
Completed a Challenge.
Ranked up your Spartan-IV to SR-5.
Found one of the RvB Easter Eggs in Episodes 1 to 5 of Spartan Ops.
Completed a Spartan Ops Mission on any difficulty.
Completed mission 1 on any difficulty.
Found and accessed Chief's record in mission 1.
Changed your Emblem in the Spartan ID card.
Changed your Service Tag in the Spartan ID card.
Complete the Campaign solo on Legendary difficulty.
In mission 2, get significant air in the Warthog at midnight.
In mission 3, carry a UNSC weapon all the way through on Heroic or harder.
Complete mission 4 without one preventable Marine death on Heroic or harder.
In mission 5, steal a Wraith and use it to kill at least four enemy Wraiths on Heroic or harder.
In mission 6, trick or force a Hunter to fall to his demise.
In Mission 7, in solo Campaign, take out both Hunters using only the Sticky Detonator.
In mission 8, kill 3 Crawlers in one hit with the Gravity Hammer.
Save at least one Marine in Chapter 3 of Episode 2 of Spartan Ops on Heroic or harder.
Complete Chapter 4, Episode 5 of Spartan Ops without losing a generator on Heroic or harder.
In Ch 1, Ep 5 of Spartan Ops survive the enemy assault during the defense on Normal or harder.
Create and save a Custom Game type in War Games.
In Crimson DLC matchmaking, get a kill while airborne in a Warthog.
In Crimson DLC matchmaking, kill 20 enemies with a detached Machine Gun Turret.
In Crimson DLC matchmaking, kill a player while airborne from a Man Cannon.
In Crimson DLC matchmaking, kill 20 enemies using the Mantis' stomp attack.
In Crimson DLC matchmaking, board an enemy Mantis.
In Crimson DLC matchmaking, score the killing blow on a Mantis.
In Crimson DLC matchmaking, shoot an enemy who’s airborne from a Man Cannon.
In Crimson DLC matchmaking, kill an enemy with melee when landing from a Man Cannon.
In Majestic DLC matchmaking, assassinate an enemy who's in zoom mode.
In Majestic DLC matchmaking, perform 5 'airsassinations.'
In Majestic DLC matchmaking, get the 'Close Call' medal twice during one match.
In Majestic DLC matchmaking, kill 5 enemies while Promethean Vision is active.
In Majestic DLC matchmaking, kill 5 enemies while Active Camo is active.
In Majestic DLC matchmaking, get a Double Kill or higher with one Pulse Grenade.
In Majestic DLC matchmaking, get 4 kills using the SAW without dying.
In Majestic DLC matchmaking, kill 3 enemies while they are using Jet Packs.
In Majestic DLC matchmaking, call in 3 ordnance drops during the same game.
In Majestic DLC matchmaking, perform a melee kill right after using Thrust Pack.
In Castle DLC matchmaking, disable a vehicle and then hijack it.
In Castle DLC matchmaking, get two direct Spartan Laser kills in one match.
In Castle DLC matchmaking, heal a near-death teammate with Regen Field 5 times.
In Castle DLC matchmaking, assassinate an enemy who is using a Hardlight Shield.
In Castle DLC matchmaking, disintegrate 6 enemies using Forerunner weapons.
In Castle DLC matchmaking, perform 5 melee kills in a single match.
In Castle DLC matchmaking, complete a match in any mode for each Castle map.
In Castle DLC matchmaking, destroy 2 vehicles during a single game.
In Castle DLC matchmaking, kill 5 enemies during a match by running them over.
In matchmaking, effectively camped one location without dying for a full 60 seconds.
In matchmaking, scored three times in one round of Ricochet.
In matchmaking, got four consecutive kills with the Rocket Launcher without dying.
In matchmaking, assassinate the ball carrier within five meters of your own goal in Ricochet.
In matchmaking, score by throwing the ball from 30 meters in Ricochet.
In matchmaking, survive three vehicle explosions in a row with the Survivor package.
In matchmaking, score a goal in Ricochet while taking damage with the Resistor active.
In matchmaking, recover full shields from low health with both Resistor and Recharge active.
In Bullseye DLC matchmaking, activate both electrical surge systems during a match on Vertigo.
In Bullseye DLC matchmaking, acquire the Rocket Launcher at the start of a match on Pitfall.