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