Halo Wars 2

In order to unlock this achievement, you will need to complete all five objectives (three Optional and two Bonus) and earn a gold medal in the first mission, "What Could Go Wrong?" in a single playthrough. Please refer below for a checklist of the mission's objectives.

Optional

• Expand to all base plots [0/3]
• Rescue the Reavers
• Build on all turret slows near the launching bays [0/5]

Bonus

• Capture all power nodes [0/4]
• Salvage all Covenant resources [0/10]

As for the gold medal, it may come naturally during a Normal playthrough without any active skulls so long as you complete all of the Optional/Bonus objectives and complete the mission under or close to Par Time. That being said, though, it's best to play each mission on Easy with the Nightmare Skull activated. Despite the low difficulty, this Skull will always net you enough points to obtain the gold medal.

Once you have obtained a gold medal and completed all five objectives in a single playthrough of this mission, this achievement will finally unlock.