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