What about TD3: Heart of Lone Salvation? The latest descriptions you and Bienie have given about the outside streets, courtyard and cellar sound a lot like it.
Nailed it! That's the one I was thinking of at least. Not sure why it didn't occur to me that's the one, as it's one of my favorite old school missions.
I've published a new release to bring the VR version on par with TDM's 2.0.9 beta: https://github.com/fholger/thedarkmodvr/releases/tag/v2.0.9_beta1
Still no room-scale, sorry.