W000T First HL2 map. (Methinks.)
It's a 3d skybox example. Fairly simple.
You should be able to work out how to do it, with the SDK info and this map. Just remember, in the skybox portion of the map, you're working in 1/16th scale.
VMF and BSP included. Uses Cstrike VMTs.
p.s. I'm having trouble with setting up the SDK for hl2. No materials for this file? :/
http://www.snarkpit.com/editing.php?page=tutorials&game=HL2&id=119
I never noticed that, must be new. Only the de_cbble VMF was in there when I made this.