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