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