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