I'm confused after reading this thread; the Xen levels are long in original HF, or in Black Mesa? > Unfortunately, by the end of the earth levels and certainly

I'm confused after reading this thread; the Xen levels are long in original HF, or in Black Mesa? > Unfortunately, by the end of the earth levels and certainly on Xen, the levels switch over to original designs By original designs, do you mean HF1 version, or pre-HF1 designs that didn't get implemented in HF1?