Played up until right before 'The Swamp'. Premise is decent enough, Doom/Chex Quest-style game with hub world. There's a bit of a visibility problem, though, as I'll often find myself unable to find where to go next due to nearly every wall and floor tile being the exact same. There's no directional feel to the map, so if you get turned around it'll take a while to figure that out.
The non-euclidean element was interesting, reminded me of some maps for Duke 3D. You could always use that in your normal maps to prevent players getting lost. Other than that, all I can comment on is that nearly invisible and disguised enemies feel a bit cheap.