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