Unlockable - Trophies
There are 7 Bronze Trophies, 4 Silver Trophies, and 1 Gold Trophy.
Touch Base (Gold) - Complete 'Return to the Military Base'
A Legion of Zombies (Silver) - Kill 500 zombies in one level
Can't touch this (Silver) - Complete a Base quest without taking any damage
Getting to know each other (Silver) - Complete all character quests
The Collector (Silver) - Complete 'Dev Card Hunt!'
Back with the X (Bronze) - Witness Rachel joining the group
Big Brain Brian (Bronze) - Witness Brain joining the group
Fists of Fury (Bronze) - Kill a mutant with your fists
Kill a zombie (Bronze) - Kill a zombie
Master Craftsman (Bronze) - Fully upgrade a weapon with any status effect
Thought this was a Zombie Game? (Bronze) - Witness Luxo joining the group
Watch this! (Bronze) - Use your first Smart Bomb