Codename DEngine is an engine for dungeon crawler game I am working on. And, No, not since the great Grimrock came out. I worked on this for quite some time now primarily as a stepping stone in the work game engine development and learning OpenGL shaders. It started as a pure python project and then I moved over to C++. There where even a version running on the Nintendo NDS for a while.
With Qt capabilities to render widgets on top of OpenGL there is a quick way now to add GUI mock ups quick on top of the engine. Later one can use Quick to do a proper GUI.
The render engine is deferred. After the initial geometry pass there are several passes for each light in the scene or e.g. rendering a daylight pass. The final passes are for gamma correcting, exposure, and other screen space techniques.