Half-life bsp?
Well considering that the data Irrlicht will use from a bsp is purely going to be the structural data it doesn't matter which format you load, it'll end up the same. I don't think any entities are loaded, and even if they are you have to implement support for them in your game/engine. So since it doesn't matter which is used, and since GFXstyLER might be right, you might as well use Quake based BSPs.
In any case if its trouble with the level builder that you're having then see if your level builder can export to MAP. If so there's a program called q3map2build.exe which will build a Quake 3 map from a MAP file.
Also, GMax, with the Game Level Builder tools can export to MAP files, so you can build levels in GMax (which is what I do)
In any case if its trouble with the level builder that you're having then see if your level builder can export to MAP. If so there's a program called q3map2build.exe which will build a Quake 3 map from a MAP file.
Also, GMax, with the Game Level Builder tools can export to MAP files, so you can build levels in GMax (which is what I do)