Full list of all 73 Halo 5: Guardians achievements worth 1,250 gamerscore. It takes around 40-50 hours to unlock all of the achievements in the base game.
The base game contains 65 achievements worth 1,000 Gamerscore, and there are 2 DLC packs containing 8 achievements worth 250 Gamerscore.
Finished Evacuation within 18:00 without dying on Heroic difficulty.
Kept 6 miners alive at the elevator in Evacuation on Heroic difficulty.
Teamed up in a vehicle to kill 30 enemies in Unconfirmed co-op.
Won a match on all three original Warzone maps.
Completed Glassed without any players using Smart-Link.
Completed 5 matchmade games of Capture the Flag.
Completed 5 matchmade games of Breakout.
Completed every Mission of the game on Normal difficulty.
Completed every Mission of the game on Heroic difficulty.
Completed every Mission of the game on Legendary difficulty.
Completed every Mission of the game by yourself on Legendary difficulty.
Completed Mission 15.
Found and claimed all Intel.
Found and claimed all Skulls.
Used a Ground Pound on an exterior power core in Guardians on Heroic difficulty.
Completed Mission 14.
Completed Mission 13.
Completed any Mission with 3+ Skulls active on Heroic difficulty.
Finished the 13th mission without losing the Scorpion on Legendary difficulty.
Completed Mission 12.
Completed Mission 11.
Completed Mission 10.
Escaped the doomed Kraken by jumping onto a Phaeton piloted by a Spartan.
Simultaneously assassinated two Elites in Blue Team co-op.
Completed Mission 9.
Completed Mission 8.
Destroyed 10 walls or floors in Swords of Sanghelios.
Completed Mission 7.
Traversed the canyon without a Phaeton in Reunion on Heroic difficulty.
Destroyed the Phantom at the Covenant camp in Reunion on Heroic difficulty.
Completed Mission 6.
Completed 5 matchmade games of Slayer.
Killed a Legendary Boss in Warzone.
Completed Mission 5.
Killed an enemy that's had its armor repaired in Unconfirmed.
Completed Mission 4.
Completed Glassed without entering a vehicle.
Completed Mission 3.
Completed Mission 2.
Escaped the Hunters in the lab and fought them in the hangar in Blue Team.
Completed 3 matchmade games of Warzone.
Opened a Gold REQ Pack.
Called in a REQ that costs 5 Energy or more.
Completed Mission 1.
Completed any co-op Mission on Heroic difficulty.
Found and claimed a Skull.
Commanded your team of Spartans in Osiris.
Found and claimed one piece of Intel.
Changed your Spartan's gear in the Spartan Hub.
Changed your Emblem in the Spartan Hub.
Changed your Service Tag in the Spartan Hub.
Create and save a Custom Game.
Spectate a game.
Complete 5 matchmade games of Strongholds.
Help the Elite General charge the hill in Osiris on Heroic difficulty.
Complete Swords of Sanghelios co-op with both Mantises on Heroic difficulty.
Complete Enemy Lines without destroying a Kraken turret.
Kill a Grunt and smash a grate with a Ground Pound in Battle of Sunaion.
Knock two Hunters into the ocean during the Battle of Sunaion.
Operate four different vehicles at once in Mission 13 on Heroic difficulty.
Complete The Breaking on Legendary difficulty without the entire fireteam dying.
Simultaneously kill two Wardens in The Breaking on Heroic difficulty.
Simultaneously destroy 2 cores in Guardians on Heroic difficulty.
Complete every co-op Mission on Heroic difficulty.
Qualify for a Competitive Skill Rating.
Beat the par time of a mission in Score Attack.
Completed a mission in Score Attack with at least 10,000 points.
Reach 50,000 points in Score Attack with a Skull multiplier of x2 or higher.
Complete a mission in Score Attack co-op, with all participants scoring at least 200,000 points.
Complete a mission in Score Attack with at least 500,000 points.
Earned a Mythic Boss Takedown in a Warzone Firefight match.
Successfully complete 5 Warzone Firefight matches.
Complete a Warzone Firefight match on 6 unique maps.