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