Here is the full list of all 18 Knock-knock achievements.
Turned into a doppelganger
Managed to hide succesfully ten times
Chose to go into the woods
Saw all fragments of reality
Remembered the story of the Lost Child
Found five diary pages
Entered a breach
Chose to lock The Lodger inside the cabin and remain hidden
Entered ten haunters
Found a diary page
Saw three fragments of reality
Touched the weeping one
Entered a haunter
Saw a fragment of reality
Managed to hide succesfully five times
Managed to hide succesfully
Turned the light on in every room
Turned the light on in a room before a breach opened