Firstly, this isn't strictly DOOM-related so it might not belong here.
Over the weekend I found myself without an internet connection so I decided to try something I had been meaning to get around to doing for a couple of years now; Hacking apart Shadowcaster to see just how far it's engine had evolved from that used for Wolfenstein3D.
Shadowcaster can in many ways be considered as a "missing link" between between the Wolfenstein3D and DOOM engines. Perhaps not on a tec