Are there any tutorials or libraries for loading BSP maps made with the Valve Hammer Editor (and compiled with ZHLT)? There's a description of the file format for the Source engine's BSP's: http://www.geocities.com/cofrdrbob/bspformat.html But that is too hard to understand... is there something simpler? Maybe I could use some tutorial from loading Quake 3 BSP's? Alternatively, is there any better map format I could use (that comes with an editor)? A preferably simpler one?

Thanks a lot. Much appreciated.

I did write a Quake 3 map loader once. Loading the BSP files themselves is fairly easy - it's much more annoying to have to load and parse the custom shader files Quake 3 uses (have a look here).

That's okay, I don't use shaders anyway. I won't be using any advanced stuff from the BSP, all I need is the vertices, faces, and texturing, and later I will add lighting, entities, portals, leafs, nodes, clusters, areas, and whatever I need for collision detection.

I'm using this for my zombie game project by the way... it's supposed to be a cross between Grand Theft Auto and the 'zombie infection' mod for Counter-Strike 1.6... cool, huh? If I can get it to work... :D
It's supposed to be about a city full of zombies where you can do most of the things like in GTA, but will be more of a shooter game like CS.