Here is the full list of all 12 Dead Ahead: Zombie Warfare trophies - there are 7 bronze, 4 silver and 1 gold.
Complete any mission with 3 stars
Kill any zombie with a blue barrel
Upgrade any unit
Kill 100 zombies
Kill any zombie with a machine gun
Open a military pack
Buy any item from the merchant
Kill Undead with a Molotov cocktail
Find 20 items
Meet the Robber
Use nitrogen to freeze at least three zombies
Reach rank 12