Here is the full list of all 19 Action Alien achievements.
Kill 100 aliens.
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.
Use every weapon during one game.
Empty all the rounds of a revolver with only deadly shots in less than 5 seconds.
Kill an alien with the last bullet of a machine gun or an assault rifle.
Demolish a part of a building with the grenade launcher.
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.