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