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.
Complete the petrol station map.
Complete the tropical hotel map.
Kill 15 boss aliens.
Unlock all perks.
Complete the wasteland map.
Blow up 500 aliens with grenades.
Kill 1 000 aliens.
Beat 100 aliens with leg kicks.
Demolish a part of a building with the grenade launcher.
Blow up 8 aliens with one grenade.
Kill an alien boss with the pistol.
Use every weapon during one game.
Kill 100 aliens.
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.