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