Here is the full list of all 27 The Crooked Man achievements.
Beat the game twice
Go back to bed without answering the phone
Beat the game once
Beat the game without drinking the energy drink
Finish Scene 4
Get Bad Ending 4
Get Bad Ending 3
Finish Scene 3
Don't miss a single shot at the Crooked Man
You shot Fluffy
Read the books in the hospital day-room
Defeat the Crooked Man in Scene 2 without taking any damage
Finish Scene 2
Get Bad Ending 2
Try to enter the bed next to D's bed
Try to enter D's bed
Get killed by poison gas
Escape the gas with over 1 minute to spare
Get Game Over 5 times
Read the books in the school
Finish Scene 1
Defeat the Crooked Man in Scene 1 without taking any damage
Get Bad Ending 1
Get Game Over once
Survive first encounter with the Crooked Man
Read the books in the hotel library
Finish the Prologue