Here is the full list of all 19 Action Alien achievements.
Earn a total of 10 000 credits.
Kill 10 000 aliens.
Unlock all golden weapons.
Unlock all upgraded weapons.
Blow up 500 aliens with grenades.
Unlock all perks.
Complete the petrol station map.
Kill 15 boss aliens.
Complete the tropical hotel map.
Beat 100 aliens with leg kicks.
Blow up 8 aliens with one grenade.
Kill 1 000 aliens.
Complete the wasteland map.
Kill an alien boss with the pistol.
Use every weapon during one game.
Demolish a part of a building with the grenade launcher.
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.