Zandronum is a free open-source advanced multiplayer sourceport capable of running various games such as Doom, Doom II, Final Doom, Heretic, Hexen, and as well as others online. It originated from Skulltag, which was based on ZDoom and its counterpart, GZDoom.
This is an old verison of PsychoPhobiaCM (Contend Mod) Version 2.01. But unlike new versions its compatible with Zdoom, and Zandronum (not just GZDoom).