Thread:Vorknkx/@comment-26005008-20150729053117/@comment-1496755-20150729055844

But of course - PoP is not included in the Steam version.

The reason for this is that Hexen II's publisher is (officially) id Software, however PoP was published by Raven Software independently. And maybe that's why it wasn't included on Steam (different copyright holder).

Thus, if you want this mission pack, you have to get it from somewhere else...