I like your clever use of a bitmap to represent level data. That's similar to how Wolfenstein 3d was developed.
I'm getting a fairly low frame rate on my machine. Have you looked at performance or optimizations at all? I'm curious where any bottlenecks could be.
The dark and thick fog makes it hard to see much, but that really does set a specific mood. There doesn't appear to be a whole lot of gameplay to support it though.
From a tech perspective, it looks impressive. I would like to be able to look at the source code, I don't see it attached in the download? Or did I just miss it?