I think those games don't fit the style of a real scary dungeon game.
i've watched 10 minutes of grimrock gameplay and realized that i had a similar idea last year:
http://www.youtube.com/watch?v=s-Chwoddb_E
I think my style doesn't fit the grimrock style, but if i would add some monsters and fighting system, it could be a cool procedural game (a maze algorithm isn't that hard)

To build some different height levels, a voroni-diagram could help to build some areas with different heights or level styles