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