Here is the full list of all 68 Zombie Army Trilogy achievements. It takes around 30-35 hours to unlock all of the achievements on Windows.
Find and shoot every Bottle of Blood
Collect every Gold Bar
Complete levels as every playable character
Complete every Survivor sidequest
Successfully complete all Chapters on Sniper Elite difficulty
Reach at least Wave 10 in Horde Mode – Waves of Despair
Reach Wave 10 in Horde Mode – Dead Man's Bluff
Kill 25 Fire Demons
Reach at least Wave 10 in Horde Mode – Cathedral
Reach at least Wave 10 in Horde Mode – Flood of Tears
Sever 10,000 limbs
Shoot the 3 Zombie Ravens outside the Folterschloss
Save the man in the hospital
Put the tortured souls in the Forest out of their misery
Reach at least Wave 10 with more gold medals than your companions
Reach at least Wave 10 with the highest score in any Horde Mode map
Kill 50 Super Elites
Kill 100 Zombie Snipers
Kill 25 Summoners
Kill 5,000 enemies of any kind
Score 5,000 with a single sniper round
Reach Wave 10 in Horde Mode – Dead End
Loot a Chainsaw Elite's corpse
Revive other players 50 times
Successfully complete Army of Darkness
Get a 5-for-1 kill with any sniper rifle
Kill 20 Elites in co-op
Reach a total shot distance of 50km
Successfully complete The Keep
Successfully complete Forest of Corpses
Kill 50 enemies that are actively attacking other players
Kill 500 Skeletons
Successfully complete Tower of Hellfire
Pick up a phone
Become possessed
Successfully complete Freight Train of Fear
Successfully complete Terminal
Successfully complete City of Ashes
Kill a Survivor
Successfully complete Gateway to Hell
Get at least 20 for 1 with an explosive kill
Headshot a Heavy Armour Zombie without removing his helmet
Successfully complete Purgatory
Loot a Super Elite's corpse
Successfully complete Subway to Hell
Kill 50 Suicide Zombies
Kill an Occult General
Get an unbroken 10-headshot streak
Successfully complete Library of Evil
Successfully complete Labyrinth of Death
Reach a Chain Count of 30
Defeat 500 enemies with headshots
Kill a Suicide Zombie by hitting his grenade
Kill a Zombie Sniper in mid-air
Sever 1,000 limbs
Kill 20 enemies as they revive
Successfully complete Cathedral of Resurrection
Successfully complete Village of the Dead
Pick up the Preacher
Get at least 15 for 1 with an explosive kill
Reach a Chain Count of 20
Kill a total of 20 enemies while incapacitated
Pick up a Panzerfaust
Kick 50 enemies down
Successfully complete Crucible of Evil
Complete any Campaign chapter in 4-player co-op at any difficulty level
Get at least 10 for 1 with an explosive kill
Reach a Chain Count of 10