Maniac Mansion? I’ve never played it, but it’s mostly/all in the titular Mansion, no?
If we count castles, Symphony of the night.
Also, the first Addams Family game for the SNES (mansion)
Well technically … two.
More like technically one, narratively two?
Control, maybe? Technically, you never quite leave the Old House, even when you do. ;)
Fatal Frame 1 (PS2)
Then we have Castle Wolfenstein, Beyond Castle Wolfenstein, and Wolfenstein 3d.
Spider: The Secret of Bryce Manor
What Remains of Edith Finch
Shadowgate. An adventure game where you explore Castle Shadowgate. These are the rooms:
Milon’s Secret Castle. A platformer, and each level takes place in a different part of the castle.
Kamaitachi no Yoru
Binding of Issac?
Oh man, I forgot all about Mr. Mosquito.
Undying takes place in a mansion and the surrounding grounds.
Jet Set Willy
Batman Arkham Asylum. That Asylum is one big mad house.
Grounded? Does one backyard count?
One backyard with a pool and one roof?
The Game of Thrones Telltale game revolves around a single House Forrester. Other Houses do come and visit though, so maybe it doesn’t count.