If you don't mind free flowing dungeons, then the intermediate step between Dungeon Master/EoTB style games and Wolfenstein/Doom style shooters is probably the old PC classics, Ultima Underworld 1 & 2. Technically it was much more advanced than Wolfenstein which it inspired, causing a much higher set of spec requirements, but both work fine under DoSBox!
Ultima'ry goodness can be seen here:
[ Show youtube player ]
Last edited by Titler; 23 November 2009 at 03:00.