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