Here is the full list of all 26 Excubitor achievements.
Pick up 1 powerup
Pass the tutorial level
Get 10000 voidshards
Get 250000 voidshards
Get 600000 voidshards
Get 500 kills
Get 2000 kills
Get 5000 kills
Get a blast from the past
Best confetti
Parteh time
Bro?
Light a bonfire
Completed chapter 1
Completed chapter 2
Completed chapter 3
Completed chapter 4
Capture 1 voidshard container
Max out the shield system
Max out the armor system
Max out the engine system
Max out the weapon system
Fully upgrade everything
Fully upgrade a weapon
Fully upgrade a turret
Pass all levels in New Game+