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