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