Screenshots of what you're doing.

that looks good is it possible to make the skybox-resolution an option? or integrated in texture quality...

are you only working on the skybox or on the whole map? cause i found some small things:
theres a part of the left side of the first picture illuminated, but nowhere else is light, this is wrong
there are vertical stripes at the wall, which is too regular, but i guess it's too difficult to make it more messy with the textures...
the floor-texture of the first picture has really low quality.
and the change from the stairs to the wall is too abrupt.


and a technical question: is something in the skymap a "valid" light source for hdr?