I want to take a crack at modding most or all of the id Software games sometime before I die. I've had an epic storyline cooking in my brain in which each (full) game would progress the story and expand the universe as the modding technology progresses. But lately I realized how unrealistic that idea is, so I've switched gears to something more manageable, like making one 9 level episode in Wolf3D, then moving on to DOOM to do another small single episode run, etc., etc.
Anyway, working with Wolf3D is challenging in a fun way. The default palette is terrible, the level design is extremely limited, and adding resources can be a hairy experience.
