Here is the full list of all 26 Othercide achievements.
Discover all story chapters
Defeat every boss in a single recollection
Defeat The Surgeon
A Scythedancer has been germinated
Reach the chrono map
Finish the tutorial by defeating all enemies
Activate all Remembrances
Defeat Suffering
Defeat The Child
Sacrifice a Daughter
Sacrifice a Daughter with one memory attached
Defeat The Maid
Add one memory to a Daughter
Spend 4000 vitae
Sacrifice a Bright Soul
Have a level 15 Daughter
Defeat The Deacon
Save a Bright Soul
Close the first Synapse
Close 20 Synapses
Resurrect one Daughter
Start a new Recollection
Earn 5 traits on the same Daughter
A Daughter is killed in battle
Lose 400 HP because of reaction or interruption skills
Kill 300 enemies