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