Here is the full list of all 75 Halo Wars: Definitive Edition achievements.
Complete any Campaign Mission in Co-op Mode.
Win 100 Skirmish or Multiplayer Matches.
Win 75 Skirmish or Multiplayer Matches.
Win 50 Skirmish or Multiplayer Matches.
Win 40 Skirmish or Multiplayer Matches.
Complete the Campaign on Heroic Difficulty.
Complete the Campaign on Legendary Difficulty.
Finish all missions under Par Time on Heroic difficulty.
Play Halo Wars for at least 24 Total hours.
Get 20,000 points in any Skirmish Game.
100% Completion.
Finish five missions under Par Time on Heroic difficulty.
Win a game on every Skirmish Map.
Win 30 Skirmish or Multiplayer Matches
Unlock All Timeline Events.
Win 20 Skirmish or Multiplayer Matches
Get a Gold Medal with all Debuff Skulls Active.
Get a Gold Medal on every Campaign Mission.
Collect all Skulls.
Kill 20 enemy squads with a continuous Covenant Leader Power on Memorial Basin.
Finish with 5000 net resources tributed to your teammates on Memorial Basin except in Deathmatch.
Hot drop 50 squads to your Covenant Leader in a single game on Barrens.
Get a Scarab during a Reinforcement game.
Win and never trail in a Tug of War game.
Score the winning point in a game of Keepaway against Legendary AI's.
Mission 14: Don't claim an extra base.
Mission 8: Use Elephants to train 100 infantry.
Mission 7: Do not destroy any Power Node.
Mission 5: Jack 6 Covenant Vehicles.
Obtain a lifetime campaign Score over 1,000,000.
Mission 2: Destroy every Methane Tank.
Mission 1: Ram and kill 50 Grunts with Warthogs.
Collect 8 Skulls.
Mission 10: Distrupt all Tractor Beams.
Mission 6: Successfully protect every Rhino.
Mission 4: Save Adam.
Disrupt 5 active Leader Powers in a single game on Blood River.
Win a Heroic Skirmish Game against the AI in under 10 minutes.
Finish one mission under Par Time on Heroic difficulty.
Mission 11: Save all the Airlocks.
Win a Skirmish Game with every Leader.
Win 10 Skirmish or Multiplayer Matches
Win a game in every Skirmish Game Mode.
Get a winning High Score with 10 or less Squads against the Heroic AI.
Unlock 20 Timeline Events.
Gain at Least 15 population from a single wave in a Reinforcement game.
Improve your Score in any Campaign Mission.
Mission 3: Kill at least 5 Covenant Units with the Bridge.
Use one of the 6 Major Leader Powers to destroy an enemy's last unit.
Completed Mission 15 on any difficulty.
Mission 15: Open the Doors in order.
Completed Mission 14 on any difficulty.
Completed Mission 13 on any difficulty.
Mission 13: Destroy 25 units with the Scarab.
Completed Mission 12 on any difficulty.
Mission 12: Repair the Power Core in less than 4 minutes.
Completed Mission 11 on any difficulty.
Completed Mission 10 on any difficulty.
Completed Mission 9 on any difficulty.
Mission 9: Put every Colony in Hibernation Mode at the same time.
Completed Mission 8 on any difficulty.
Completed Mission 7 on any difficulty.
Completed Mission 6 on any difficulty.
Completed Mission 5 on any difficulty.
Completed Mission 4 on any difficulty.
Completed Mission 3 on any difficulty.
Win a Public game.
Win and have the highest score in a Public Game.
Completed Mission 2 on any difficulty.
Collect your first Skull.
Get a Gold Medal on any mission.
Completed Mission 1 on any difficulty.
Win a 3v3 Skirmish game with 2 AI Allies.
Win a Skirmish Game with Dual Scarabs.
Unlock a Timeline Event.