I bought Hauntify today ($4.99 on Itch.io) while I was at work (in a classroom with a Quest 2).
The wall placement and interface needs some work, but the mechanic of the ghosts being occluded by walls works really well. I only tried it a little (and when the ghost got me the map was wiped, I didn't do the right thing to save it).
It's interesting that it darkens the environment and gives you a flashlight (that really restores normal lighting). I'm guessing it's an alpha blend with black except where the light is.
I ended up out in a hallway of the college placing wall pieces, reassuring the occasional passerby that they were safe, I could see them.
With v34 Quest software supporting passthrough better, I'll have to try some dev myself.