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