Here is the full list of all 21 Zomborg achievements.
First kill a robot
Discovered research evidences for the first time
Kill 100 zombies
Kill 50 zombies
First kill a zombie
Kill 500 zombies
Kill 1000 zombies
Kill 10 robots
Kill 30 robots
Kill 50 robots
Unlock all weapons
Unlock all buddys
The mission is complete with buddy without anyone dying
Win 3 missions alone
Unlock PKM gun
Unlock RPG gun
Unlock SSG3000 gun
Discovered a usable helicopter for the first time
Eliminated "Jackson" the leader of cyborgs
Discover the secret factory
Eliminated "Jason" the leader of cyborgs