Halo Wars 2

In Halo Wars 2, every mission objective you complete, whether it's Primary, Optional, or a Bonus, will net you a few thousand points to your overall mission score. On top of this, your overall performance (how many Units you lose during the mission) and speed of mission completion will largely impact your overall score, too. Finally, activating specific Skulls that increase the difficulty of gameplay, such as Pestilence, Sickness, and Nightmare, will also impact your score.

Every mission has three medals: Bronze, Silver, and Gold. For the purposes of this achievement, you will need to obtain a gold medal on every mission except the Prologue, "The Signal." There is no one way to get this done. Some gold medals may come naturally during a Normal playthrough with no skulls activated; sometimes, so long as you complete a few Optional and Bonus Objectives along the way, the gold medal will be yours. It's also worth noting that gold medals obtained in Co-Op playthroughs count towards this achievement. Again, there are numerous ways to go about it.

All in all, if you need to return to a mission after your initial playthrough in order to snag its gold medal, play the mission on Easy and make sure the Nightmare Skull is activated. Despite the low difficulty, this Skull will usually always net you enough points to obtain the gold medal.

Once you have obtained a gold medal in all eleven missions outlined above, this achievement will finally unlock.