The theme was a great idea and the visuals work really well for it.
The problem is there's control issues:
Pressing esc to return back into the walls conflicts with pressing esc to disable fullscreen.
A 3d browser game should have an option for camera speed because it's too hard to get that right for everyone first time around.
There was no real difficulty in terms of gameplay aside from fighting with the camera.
This is a great idea for a game that just needs gameplay improved.