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