Doom Guy: Life in First Person

by John Romero

It was November, and we were releasing in a month. I brought it up to Carmack. “So when are we going to make multiplayer mode?” The short answer was that Carmack was ready to take it on. Looking from the outside in, I suspect some might wonder if I wasn’t just more than a bit concerned since we were hoping to ship in 1993. After all, John had never programmed a multiplayer game before. The truth is that I never had a doubt, not for a second. Back in March, Carmack had already done some innovative network programming in DoomEd. He wanted to play around with the distributed objects system in NeXTSTEP, so he added the ability to allow multiple people who were running DoomEd to edit the same level. I could see him drawing lines and placing objects on my screen from his computer. Then, I’d add to his room by making a hallway, and so on. For multiplayer, Carmack’s plan was to explore peer-to-peer networking. It was the “quick and dirty” solution instead of a client-server model. Instead of one central computer controlling and monitoring all the action between two to four players, each computer would run the game and sync up with the others. Basically, the computers send each other updates at high speed over the local network. The speed of Carmack’s network programming progress was remarkable. He had some excellent books on networking, and fortunately, those books were clearly written and explained the process of using IPX* well. In a few hours, he was communicating between two c...