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 mission 4 without one preventable Marine death on Heroic or harder.
In Ch 1, Ep 5 of Spartan Ops survived the enemy assault during the defense on Normal or harder.
Got significant air in the Warthog at midnight in mission 2.
Killed 3 Crawlers in one hit with the Gravity Hammer in mission 8.
Stole a Wraith and used it to kill at least four enemy Wraiths in mission 5 on Heroic or harder.
Completed all chapters in any 5 episodes of Spartan Ops on any difficulty.
Completed Chapter 4, Episode 5 of Spartan Ops without losing a generator on Heroic or harder.
Carried a UNSC weapon all the way through mission 3 on Heroic or harder.
Created and saved a Custom Game type in War Games.
Uploaded a File to your File Share.
Saved a Film Clip from the Theater.
Saved a Screenshot from the Theater.
Completed mission 1 on any difficulty.
Completed mission 2 on any difficulty.
Completed mission 3 on any difficulty.
Completed mission 6 on any difficulty.
Found a Terminal in the Campaign.
Found one of the RvB Easter Eggs in Episodes 1 to 5 of Spartan Ops.
Tricked or forced a Hunter to fall to his demise in mission 6.
Completed 25 Challenges.
Saved at least one Marine in Chapter 3 of Episode 2 of Spartan Ops on Heroic or harder.
Completed the Campaign on Legendary difficulty.
Completed the Campaign solo on Legendary difficulty.
Took out both Hunters using only the Sticky Detonator in mission 7.
Completed the Campaign on Heroic or harder.
Completed the Campaign cooperatively on Heroic or harder.
Found all of the Terminals in the Campaign.
Completed all chapters in Spartan Ops Episode 1 on Legendary difficulty.
Completed a Spartan Ops chapter solo on Legendary.
Completed any Campaign mission cooperatively on Heroic or harder.
Completed any Campaign mission with 3 or more Skulls on Heroic or harder.
Changed your Spartan's pose in the Spartan ID card.
Won 20 War Games matchmaking matches.
Ranked up your Spartan-IV to SR-20.
Created and saved a Custom Map in Forge.
Assassinated a Knight in any Spartan Ops mission.
Completed a Spartan Ops Mission on any difficulty.
Won 5 War Games matchmaking matches.
Completed a Challenge.
Ranked up your Spartan-IV to SR-5.
Completed mission 8 on any difficulty.
Completed the Campaign on Normal or harder.
Completed mission 7 on any difficulty.
Completed mission 5 on any difficulty.
Completed mission 4 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.
Changed your Spartan's armor in the Spartan Armor card.
In Crimson DLC matchmaking, killed 20 enemies using the Mantis' stomp attack.
In Crimson DLC matchmaking, shot an enemy who’s airborne from a Man Cannon.
In Crimson DLC matchmaking, killed an enemy with melee when landing from a Man Cannon.
In Crimson DLC matchmaking, got a kill while airborne in a Warthog.
In Crimson DLC matchmaking, killed a player while airborne from a Man Cannon.
In Crimson DLC matchmaking, boarded an enemy Mantis.
In Crimson DLC matchmaking, killed 20 enemies with a detached Machine Gun Turret.
In Crimson DLC matchmaking, scored the killing blow on a Mantis.
In Majestic DLC matchmaking, kill 3 enemies while they are using Jet Packs.
In Majestic DLC matchmaking, called in 3 ordnance drops during the same game.
In Majestic DLC matchmaking, got 4 kills using the SAW without dying.
In Majestic DLC matchmaking, assassinated an enemy who's in zoom mode.
In Majestic DLC matchmaking, got a Double Kill or higher with one Pulse Grenade.
In Majestic DLC matchmaking, performed 5 'airsassinations.'
In Majestic DLC matchmaking, got the 'Close Call' medal twice during one match.
In Majestic DLC matchmaking, killed 5 enemies while Active Camo is active.
In Majestic DLC matchmaking, perform a melee kill right after using Thrust Pack.
In Majestic DLC matchmaking, killed 5 enemies while Promethean Vision is active.
In Castle DLC matchmaking, completed a match in any mode for each Castle map.
In Castle DLC matchmaking, disintegrated 6 enemies using Forerunner weapons.
In Castle DLC matchmaking, healed a near-death teammate with Regen Field 5 times.
In Castle DLC matchmaking, killed 5 enemies during a match by running them over.
In Castle DLC matchmaking, got two direct Spartan Laser kills in one match.
In Castle DLC matchmaking, performed 5 melee kills in a single match.
In Castle DLC matchmaking, destroyed 2 vehicles during a single game.
In Castle DLC matchmaking, assassinated an enemy who is using a Hardlight Shield.
In Castle DLC matchmaking, disabled a vehicle and then hijack it.
In matchmaking, recovered full shields from low health with both Resistor and Recharge active.
In matchmaking, scored a goal in Ricochet while taking damage with the Resistor active.
In matchmaking, got four consecutive kills with the Rocket Launcher without dying.
In matchmaking, assassinated the ball carrier within five meters of your own goal in Ricochet.
In matchmaking, scored three times in one round of Ricochet.
In matchmaking, scored by throwing the ball from 30 meters in Ricochet.
In matchmaking, survived three vehicle explosions in a row with the Survivor package.
In matchmaking, effectively camped one location without dying for a full 60 seconds.
In Bullseye DLC matchmaking, activated 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.