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