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