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