Looking for Dark Forces custom levels was my gateway drug to the QMODEM, BBS, and news groups back in 1995. Similar to Doom's wad files, dark forces had gobs. Eventually a dos base editor, DFUSE, was released, but I remember one level creator (dons3d, I think) that came out with a level created without any gui based tools. He plotted out all the X, Y, Z coordinates for the vertices, calculated texture stitching offets, enemy locations, etc by hand. It was amazing. Just the act of adding a door that slid open involved a special scripting language, coordinate geometries, texture lining, etc.
That man was my hero. I learned so many technical and spacial skills by trying and failing to make a good custom dark forces level.
Good times.