Thief 3? I think it was 3. Shalebridge Cradle. I play that game every year with the intention of finishing. I get to the Cradle, get parts of it done, and can't finish. It's mentally taxing especially in a dark home theater with a 7.2 surround system and 110 inch wide screen. It's also physically taxing just sneaking around in the dark in that game cause it's scary as f- in that part of the game.
Definitely the Thief series. Although I never finished any of them. I think I played Thief 1 the most though.
Those games are stressful. That's why I stopped playing them.