Here is the full list of all 36 Sniper Elite: Nazi Zombie Army 2 achievements.
Defeat the Final Boss
Defeat 100 ignited zombies
Kill 5000 enemies
Defeat 20 Summoners
Defeat 10 Fire Demons
Find and shoot all the bottles of blood
Collect all Gold Bars
Kill 100 skeletons with explosives
Kill 20 Snipers in co-op
Kill 2000 enemy grunts in co-op
Kill any 100 enemy with the shotgun
Kill 20 Elites in co-op
Get a 5-for-1 kill with any sniper rifle
Defeat 500 enemies with headshots
Successfully complete Chapter 5 with 4 players
Successfully complete All Chapters 4 players on Elite Difficulty
Kill the trapped Elite
Kill 1000 enemies
Successfully complete Chapter 4 with 4 players
Defeat a Fire Demon
Successfully complete Chapter 3 with 4 players
Pick up a phone
Kill a suicide grunt by hitting his grenade
Successfully complete Chapter 2 with 4 players
Loot an Elite's corpse
Kill 500 enemy grunts
Pick up the Preacher
Successfully complete Chapter 1 with 4 players
Kick 50 enemies down in co-op
Kill 20 enemies as they revive
Become possessed
Pick up a shotgun
Get at least 10 for 1 explosive kill in 4 player co-op
Get at least 15 for 1 explosive kill in 4 player co-op
Get at least 20 for 1 explosive kill in 4 player co-op
Own 2 Nazi Zombie Army games