Here is the full list of all 27 Abandoned: Chestnut Lodge Asylum achievements.
Complete the game within 4hrs
Complete all puzzles without SKIP
Complete all HO scenes without HINT
You've found a changing object 22/22
Collect 5 items within 10 seconds
You've found a changing object 21/22
You've found a changing object 20/22
Visit 6 patient rooms
You've found a changing object 19/22
You've found a changing object 18/22
You've found a changing object 17/22
You've found a changing object 16/22
You've found a changing object 15/22
You've found a changing object 14/22
You've found a changing object 13/22
You've found a changing object 12/22
You've found a changing object 11/22
You've found a changing object 10/22
You've found a changing object 9/22
You've found a changing object 8/22
You've found a changing object 7/22
You've found a changing object 6/22
You've found a changing object 5/22
You've found a changing object 4/22
You've found a changing object 3/22
You've found a changing object 2/22
You've found a changing object 1/22