Here is the full list of all 22 Typing of the Undead achievements.
Kill 300 Zombies
Die.
Kill 100 Zombies
Kill your first Zombie
Use your Special for the first time
Use your Special 10 times
Use your Special 100 times
Defend your location for 10 waves
Defend your location for 20 waves
Defend your location for 30 waves
Defend your location for 40 waves
Defend your location for 50 waves
Defend your location for 100 waves
Die 10 times
Die 50 times
Die 100 times
Kill 500 Zombies
Kill 750 Zombies
Kill 1000 Zombies
Do a Headshot!
Find yourself a Secret Gift!
Get yourself a Trophy!