Here is the full list of all 50 Warhammer 40,000: Space Marine II achievements worth 1,000 gamerscore.
Overcome every challenge and achieve ultimate victory
Rise as a Primaris
Destroy the hive ship with the power of anti-aircraft batteries
Discover the Chaos presence on Kadaku
Ascertain the location of Morias Leuze
Rescue Morias Leuze from the Chaos assault
Defeat the Chaos sorcerer
Hear all of the Chaplain's dialogues
Hit [10] objects during the sub-orbital drop
Discover the true nature of the Aurora device
Withstand and overcome the Chaos invasion
Defeat the Lord of Change and face a figure from the past
Mark every enemy type
Perform [50] unique Finishers
Collect all Dataslates
Kill [100] enemies using Righteous Fury
Deploy a bomb in the promethium well to destroy the Tyranid swarm
Deliver a nova cannon warhead to the Tyranid position
Kill the Hive Tyrant
Eliminate the Daemonhost and restore vox communication
Destroy the Chaos warp beacon
Reanimate The Sword of Atreus
Complete any Mission in Operations mode on Ruthless Threat Level
Find [200] pickups in Operations mode
Reach the maximum Level for one Class
Reach the maximum Level for one Melee Weapon
Reach the maximum Level for one Ranged Weapon
Customise a full Armour set for one Class
As a Tactical, kill [25] enemies with every available Primary Weapon
As a Sniper, make [250] Headshots
As a Heavy, kill [500] enemies while in Heavy Stance
As an Assault, hit [500] total enemies with Ground Pound
As a Bulwark, kill [100] enemies with every available Melee Weapon
As a Vanguard, perform [100] Gun Strikes
Force a Ravener to release a grabbed Squad Member
Bring down a Lictor before it attacks from an ambush
Kill a Lesser Sorcerer while he's reviving a Rubric Marine
Break a Scarab Occult Terminator's Melee Combo Attack with 2 Perfect Parries in a row
Kill [100] enemies using environmental hazards
Kill [5] enemies while they are conducting a Call for Reinforcements
Kill 1,000 Tyranids in Operations mode
Kill 1,000 Chaos servants in Operations mode
Kill [20,000] enemies (all game modes combined)
Kill 41,000 Enemies (all game modes combined)
Win any match in Eternal War mode
Win a match in Eternal War mode with every Class
Play [10] Annihilation matches in Eternal War mode
Play [10] Capture and Control matches in Eternal War mode
Play [10] Seize Ground matches in Eternal War mode
Achieve a streak of [5] kills without dying in Eternal War mode