I'm sorry to bring this up again, but I'd like to understand the real cause for your inability to produce destructible environments. I have seen the func_breakable, but that doesn't really seem to be a viable solution for creating an entirely destructible map. As far as I could understand it's more of a way to add some destructible objects.
I know next to nothing about the project, but I have tried the game under linux and I have to say that it's very good. I don't have an immense amount of free time on my hands, but I've done a good bit of c/c++/python/java/opengl coding and wanted to consider developing a solution to this particular problem, that I find most interesting.
As far as I understand the graphics engine being used is a heavily modded version of the Q2 engine (please correct me if I am wrong). I've also read that inability to create destructible environments is buried somewhere in the engine. Clearly it's possible to rewrite the engine code as needed and retain backwards compatibility, at worst through an additional abstraction layer.
Basically - someone point me in the right direction to start looking at possible solutions to this problem. That probably includes engine source that you use (which is probably there, I just don't know where). Thanks.