Here is the full list of all 35 The Last Stand: Aftermath achievements.
Lower the bridge in Leighton City
Kill a Spitter
Reach The Sunken City
Activate the radio tower
Collect 25 Supply Bags
Trigger a trap, with fatal consequences
Use Antiviral 25 times
Kill a Charger
Survive in No Man's Land
Kill 1000 Infected
Kill a Burster
Kill a Leaper
Reach The Mountains
Open the gates at the HERC checkpoint
Craft 25 items at a crafting stations
Died 10 times
Collect 100 Knowledge
Reach Level 10
Spend Knowledge points to max out a skill upgrade
Purchase an item from the travelling merchant
Craft an improvised weapon
Craft an item at a crafting station
Interact with a Supply Cache
Discover the modified HERC device
Survive a Horde
Kill a Volunteer
Acquire a mutation
Complete the tutorial
Reach Hell
Reach Level 50
Reach Level 100
Kill a Flamer
Kill an Armored Charger
Complete the main quest line
Complete 5 Runs