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