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