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