This is my hobby engine that I've been working on. It supports maps exported from Blender (crummy and not shown because I suck with 3D modelers) and GtkRadiant maps. Both the maps shown are Radiant maps, the first one was compiled and converted to my format through a converter and the second was compiled from Radiant's internal map format (.MAP). The second image shoes some per-pixel lighting I was fooling around with a bit, I used GLSL for the lighting and it's about the simplest lighting method possible. (I'm not joking)
Something interesting about my .MAP compiler, for anyone who knows how the format is stored (for those who don't, it's a bunch of planes that are tested for the intersections among themselves), I didn't do the standard method of getting the vertex coordinates. What I did was created a giant cube, then clipped the planes to that. It's pretty fast and there's no need to check for degenerate geometry like with the plane-intersection method.
There is a console that isn't shown in the screenshots where you can change engine settings and load maps. All of the windowing and input is done using SDL so it's cross-platform, in fact, the project started on Linux and that's why I had a Blender map converter. I did all the textures in the second shot and am kind of proud of that considering how good I am at art. (I can honestly say I think everyone reading this would be a better artist than me)
I don't think I'll be working on this project much anymore because I'm now working with a small team on getting a small game out the door, so keep your eyes open for that. Like most developers, I find it frustrating creating the engine, the game and all the data (worlds, textures, models, skins, animations, sound FX, music, etc.) by myself, so I think I'm going to stick with working with others, even though I don't get to excersize full creative license on everything.
Sorry about the low quality of the images, I had to do some resizing and it got a bit ugly. I think I've covered all the bases, but if anyone has any questions, feel free.