Full list of all 15 Claire: Extended Cut achievements worth 1,000 gamerscore. It takes around 6-8 hours to unlock all of the achievements on Xbox One.
Complete 'Normal" mode.
Get the A Ending.
Find 13 butterflies.
Defeat the Glower.
Find 14 notes.
Complete the School.
Visit somewhere else.
Find a bunch of items.
Complete the Hospital.
Find 3 butterflies.
Find 3 notes.
Survive.
Answer the phone.
Complete 'Nightmare" mode.
Find all Troublemaker cutscenes.