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