In The Room: Old Sins
The events of The Room: Old Sins take place in Waldegrave Manor, with the exception of the ending cinematic. Shortly before the game starts, Collector Hydrus searches the manor for the Null sample loaned to Edward Lockwood by The Circle. The attic is the last place he checks. Here, he encounters Abigail Lockwood's childhood dollhouse, warped by the Null to resemble Waldegrave Manor.
Studying the dollhouse, Hydrus discovers that the Null sample he is looking for is sealed within it. He also finds that he can use his eyepiece to superzoom inside the individual rooms of the miniature Waldegrave Manor. Solving puzzles one room at a time, he eventually makes it to the center of the dollhouse and extracts the Null, at which point he is returned to reality and the dollhouse reverts to its original form, not resembling the manor.
In The Room VR: A Dark Matter
The attic of Waldegrave Manor is one of the places that The Detective is sent in The Witches level. It is also seen in the Tarot Card that is used to open the portal to the manor. The Tarot Card is labeled 'Remorse' implying Edwards remorse at the end of his life. The item collected from the dollhouse is a wooden doll resembling Edward. This is the same doll that the player moves around at the end of The Room: Old Sins. A photo of Waldegrave Manor can also be seen in The Witches cottage.
The rooms that the player can examine are The Foyer, The Study, The Kitchen, The Curiosity Room, The Garden, The Maritime Room, The Japanese Gallery, The Art Studio, and The Attic. Other rooms are briefly mentioned in the books containing Edwards and Abigail's thoughts, and still more can be seen in the floor plan of the manor in Collector Hydrus' case.
The Foyer is the first room that Hydrus is able to access. It contains a fireplace, many portraits, and a single round table. In the game's first book entry, left by Abigail, she describes watching The Circle bring in Edward's scientific equipment, likely through the foyer. Edward later describes the same scene from his perspective.
In the Study are a number of elaborate scientific instruments, a safe, and a roll-top desk. The Study was once occupied by Hugo Waldegrave. Abigail fondly remembers spying on her father in his study by listening at the door or looking down through a crack in the Attic floorboards. Following Hugo Waldegrave's death, the room was taken over by Edward Lockwood, and became the base of operations for his research into the Null. Edward would lock himself inside the Study and work obsessively, much to the distress of Abigail. Her efforts to intervene eventually led Edward to change the lock on the door.
The main features of the Kitchen are a dumb waiter, a small table with chairs, a stove, service bells, and a series of water pipes. In the dollhouse, the water can be adjusted to run through the furnace, providing steam to the Study above, or through the outer wall, feeding the fountain in the Garden.