Here is the full list of all 12 All Zombies Must Die! achievements.
Complete "Return to the Military Base"
Complete "Dev Card Hunt"
Complete ALL character quests
Kill a Mutant with your fists
Fully upgrade a weapon with any status effect
Complete a base quest without taking any damage
Kill 500 Zombies in one level
Witness Luxo joining the group
Witness Brian joining the group
Witness Rachel joining the group
Use your first Smart Bomb
Kill a Zombie