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