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