I don't know much about the progression of the ZDoom modding scene. I do know that early works like Tei Tenga and Hell Factory are lauded as being watersheds of things like hubmaps and cutscenes, and I also know that Xaser's Zen Dynamics is heralded as the progenitor of most modern weapon mods in one way or another. Released in 2005 (with an update in 2006 making some major changes and adding a level), Xaser replaced every weapon in the Doom arsenal and added a few more just to give you something to think about as well as threw in a ton of new enemies for you to ponder on. At a modest ten maps, you get something of the feel of how these things change gameplay, as well as what the ZDoom engine was capable of at the time.
