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