Here is the full list of all 19 Action Alien achievements.
Demolish a part of a building with the grenade launcher.
Use every weapon during one game.
Empty all the rounds of a revolver with only deadly shots in less than 5 seconds.
Kill 100 aliens.
Kill an alien with the last bullet of a machine gun or an assault rifle.
Kill 1 000 aliens.
Kill 10 000 aliens.
Beat 100 aliens with leg kicks.
Blow up 8 aliens with one grenade.
Blow up 500 aliens with grenades.
Kill 15 boss aliens.
Kill an alien boss with the pistol.
Unlock all upgraded weapons.
Unlock all golden weapons.
Unlock all perks.
Earn a total of 10 000 credits.
Complete the wasteland map.
Complete the tropical hotel map.
Complete the petrol station map.