Here is the full list of all 19 Endless Horde achievements.
Close 100 doors
Buy the Shotgun guard
Kill 1000 zombies in one game
Kill 300 zombies using the explosive barrel
Kill 100 zombies in one game
Survive the first wave
See the Game Over screen for the first time
Kill 30 zombies in one game
Survive 30 waves in a row
Reach 3000 supplies in one game
All Scientists must survive 10 waves in a row
Buy the Sniper guard
Repair 30 doors
Place 999 Guards
Freeze 200 zombies
Place 500 Handgun guards
Place 500 Rifle guards
Buy the Rocket Launcher guard
Buy the Gatling gun guard