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