Halo Wars: Definitive Edition

Update: The much faster and mostly easier mission is mission 12! Thanks Aco2148117 for reminding me about that mission.
You can even do it on Legendary with the same strategy. Simply spam build Cyclops and run them to the objective to repair it and try to protect them with your other units. I think a time of one and a half minutes is possible if I remember correctly!

To access the Co-op Campaign lobby, you can either select Campaign or Multiplayer from the Main menu. Under Campaign, select Co-op and it'll put you into the Co-op lobby search screen.
If Multiplayer, change the Game Type to Campaign, or Create your Campaign lobby.

It's hard to find someone random to play with, so find a boosting partner.

The easiest and fastest mission is Mission 1: Alpha Base. Simply run through it on Easy, turn on the helpful Skulls if you have them to make it even easier, and you'll be done in less than 4 minutes!

The easiest way to complete this by playing Mission 12: Repairs on easy.

Set your global rally point to the place you need to repair and just keep spawning cyclops from both airlocks. Make sure you after they spawn to tell them to repair and keep your focus on the cyclops. After you have about 15 cyclops just start throwing heals on them to speed up the process

I send my entire starting army to protect my cyclops and leave the hawks by the airlocks. The covenant shouldn't give you to much trouble.
Should take about 45 secs and you will get a gold medal.

Hardest part is finding a buddy to play, good luck.

Easy boosting method, alone, with only ONE Xbox

You can do this coop achievement alone if you have the following:
-Have an Xbox One / Series
-Have Xbox Gamepass Ultimate
-Have a phone or a computer

1) With your main profile, set your Xbox One / Series as your "Home" console so that any profile on it can access downloaded gamepass games without having to pay for another subscription.
2) Start Halo Wars on your Xbox One using a secondary profile.
3) Start Halo Wars using xCloud on your phone or PC with your main profile.
4) Invite your other profile, start mission one, speedrun it, unlock your achievement.

Using this, I was also able to get the 100 wins achievement in around an hour.
Works for any gamepass game if you need coop/boosting on other games!


PS: I played using an Xbox One and a computer. xCloud using Xbox Series, loading times were much shorter on xCloud than on my Xbox One !

In order to get this achievement, you need to complete any campaign mission in Co-op.

As stated by other solutions, Mission 12 is the fastest and easiest for this.

However, the biggest issue with the achievement is finding another player to help you, this happens because:

1) The multiplayer for this game is dead.
2) Even though the game is play anywhere, the PC and Xbox multiplayers are NOT Cross play, this is specially annoying if you are playing on PC, as the player base is next to zero.
3) Halo Waypoint forums are not helpful either.

This is way I’m wanted to let know anyone who might need this in the future that I have an Xbox One and PC and I’ll be more than happy to assist you. Just message me.

“Achievement Hunters need to help each other to achieve more”