Here is the full list of all 44 8Doors: Arum's Afterlife Adventure achievements worth 1,000 gamerscore.
Start of the Journey
Failed Hero
Specter of Sin
Path of Flame
Metal-Eating Monster
Saboteur
Plans
Puppet
Cries of Pain
Comrade
Purification
Punishment
Faith
Kingdom of Yama 100% complete
Stone Mountain 100% complete
Misty Forest 100% complete
Barren Grounds 100% complete
Crimson Mines 100% complete
Frozen Plateau 100% complete
Underground Waterway 100% complete
Land of Abundance 100% complete
All regions 100% complete.
Gap
Kkokdu
Obtain all Flowers of Life
Obtain all Reaper Perks
Obtain all Messenger Perks
Obtain all Pathfinder Perks
Obtain all Perks
Hidden Technique
Technical Guardian of Death
Interacted with all Dawn Tombstones
Guided all Fugitive Souls
Memory Fragment
True Memory
Friend
Belief
Greedy Person
Clear the game without dying
Clear the game without learning any other Perk except Duoxini
Complete Normal Mode in 3 hours
Standstill
Another Start
Lost Princess