I've heard that having big open volumes in your level is bad. Why is it bad? Big bsp? Can the problem be minimized by filling in inaccessable spaces with clip brushes?

There's only two facts that can made them bad, and they are strongly connected to each other: big areas full of detail will surely bring down FPS (frames per second) to unplayable levels. Big areas lacking detail may look plain and uninteresting and kill the visual artistic image of the map.

See how those too are connected in a nasty way?

Anyway, if you can design large areas with enough detail to keep them intersting and yet they still play smoothly on your computer, it's perfect and almost necessary for truly memorable maps. Also there are some ways to keep the FPS up, but that's another story.


A big bsp in itself is no problem. If you have a large map with plenty of details and nice lighting, the bsp will be big. Problems arise if you don't detail your brushes (or don't clip irregular shapes as you said yourself).

Just remember "it's all just polygons". ;)