Here is the full list of all 30 Once on a windswept night achievements. It takes around 1-2 hours to unlock all of the achievements on Windows.
You remember who you are.
Read a lonely spirit's story.
Bring the story to a premature close.
Read Daffodil's story.
The traveller refuses to tell Daffodil the truth.
Offer Daffodil a few too many compliments.
Read Madeleine's story.
Madeleine refuses to share her story.
D-Did you just insult a girl's cooking?! You monster!
Throw caution to the wind!
Listen to a mysterious voice.
The traveller leaves the church early.
Start a new story.
Take the traveller's name for your own.
Make yourself the third Madeleine.
Multiply the number of daffodils in the story.
Name yourself after a certain flower.
Try to steal Lycoris' most precious possession.
Lycoris welcomes you to her library.
Reach your happy ending.
Arrange the actors back on the stage.
Answer Lycrois' question incorrectly.
Lycoris gets a little too possessive.
Let yourself forget everything.
Wait for a play that's already over.
Return to the library for a second time.
Return to the library when Lycoris needs you the most.
Learn Lycoris' favourite flavour of tea.
Profess your love for Daffodil.
Profess your love for Madeleine.