Requires GZDoom
Requires cc4-tex.wad
(maybe ZDoom or Zandronum will work - not tested, but I can't imagine why they wouldn't)

Some anon on /vr/ saved a screenshot I posted in 2014 or so, asking about the mapset it was from. It was from an unreleased mapset I abandoned.
So I stitched it together and pushed it out into the cold.
It has seven maps. Map 3 exits into two different maps, and those maps lead into the final map, which I released separately later (so there's a small chance you've played the final map) + one secret map. It also has a secret weapon that replaces the BFG and is almost useless, and the plasma rifle has been changed a bit.   Random Screenshot:   Credits + Info you don't need