Here is the full list of all 43 Over 9000 Zombies! achievements.
Construct 1000 Turrets from random scraps of metal!
Kill 900,000+ Zombies!
Construct 100 automated turrets.
Kill 90,000+ Zombies!
The zombie world is independent of our will.
Kill over 1000 zombie eyes!
Participate in a multiplayer game.
Kill over 1000 crabs!
Abused patience turns to fury!
Health is the greatest gift, a close second is BRAINS!
Voted the greatest zombie of all time!
Derail the Waltz of the Undead!
Terror possessed me then!
If only he had the body of a horse...
A jail is an isolated system.
Blood and Flesh can be trusted.
The army of the undead will march at daybreak!
Decreased Zombotropy.
Quoth the Raven "Nevermore."
Kill over 1000 zombie crows!
Get 30 kills per second!
Don't call me slow!
Collect 100 Power Ups!
Your world didn't end!
You didn't donate your organs...
No 8th symphony for zombie Sibelius!
Kill 9,000+ Zombies!
Kill over 1000 zombie dogs!
Get 15,000 damage per second!
It didn't taste like chocolate ice cream either...
Not a wimp.
Lots of progress!
You watched the world burn, and survived. It was kind of cool.
Vote for Zombie Thomas Jefferson, or don't.
Green IS good.
Zombie Napoleon meets his zombie Waterloo!
You won that race.
Kill 1000+ Zombies!
Get 5,000 damage per second!
Making some progress...
Construct a turret from scrap metal!
The first day is always the hardest, except in this case, it's the easiest.
Get 10 kills per second!