Years ago in the early 90's I used to work at Egghead part-time for extra toy money. For those that don't remember them, they were a chain of retail stores that sold computer software & hardware. On our demo machines we would play the original PC version of Doom in LAN mode for death matches. Oh, those were fun times.
One of my favorite games out of that time, and also based on the Doom engine, was the Heretic & Hexen series. The ability of turning your opponent into a chicken was well worth the time playing.