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