Here is the full list of all 36 The Last Stand: Aftermath trophies - there are 20 bronze, 10 silver, 5 gold and 1 platinum.
Survive in No Man's Land
Purchase an item from the travelling merchant
Collect 100 Knowledge
Kill a Leaper
Reach The Mountains
Open the gates at the HERC checkpoint
Kill a Charger
Kill a Burster
Reach Level 10
Craft an item at a crafting station
Discover the modified HERC device
Craft an improvised weapon
Kill a Volunteer
Trigger a trap, with fatal consequences
Interact with a Supply Cache
Acquire a mutation
Survive a Horde
Spend Knowledge points to max out a skill upgrade
Complete the tutorial
Unlocked all trophies in the game
Reach The Sunken City
Reach Hell
Reach Level 50
Reach Level 100
Died 10 times
Kill a Spitter
Kill a Flamer
Kill an Armored Charger
Kill 1000 Infected
Activate the radio tower
Lower the bridge in Leighton City
Complete the main quest line
Complete 5 Runs
Craft 25 items at a crafting stations
Collect 25 Supply Bags
Use Antiviral 25 times