Here is the full list of all 21 Galaxy of Drones achievements.
Complete the first mission.
Complete a mission with one shield point.
Complete a mission without losing a tower.
Complete a mission without losing a mine tower.
Complete all the missions.
Complete all missions with Ben.
Complete all missions with Olivia.
Complete all missions with Anthony.
Complete all missions with George.
Complete all missions with Isaac.
Find the Ancient Green Artifact on the planets.
Find the Ancient Yellow Artifact on the planets.
Find the Ancient Red Artifact on the planets.
Find the Ancient Blue Artifact on the planets.
Find the Ancient Purple Artifact on the planets.
Complete 25 missions on planet type A.
Complete 25 missions on planet type B.
Complete 25 missions on planet type C.
Complete 25 missions on planet type D.
Complete 25 missions on planet type E.
Get the donation reward in multiplayer.