Here are some rough pictures I've drawn that may give some clue. More/better on the way.
I believe that box on the right (red fire stuff) may be a different part of the map
Here is a top vew of what Part of the map (maby 25%) may look like. The circle indicates the part i'm most confident about. The green box is some kind of risen structure. I do believe this part of the map has some sort of backwards S shape.
This might be a different level (or a different pwad) however I remembering going down light gray stirs into a circle water floor texture and battling a cyberdemon. Picture estimates scale where the horizontal line reprezents the cyberdemon. If anything the pit was bigger. The pit was about 1.5 cyberdemons deep. It was designed so that you had to constantly circle the cyberdemon. By simply dodging the rockets you would get caught in the blast from them hitting the wall.
I very well could be remembering 2 different wads however if I could find ether of them I will be most grateful.
List of atributes: (last updated 1/31/13)
1. I do not believe it had any new textures or graphics. Such as title screen for example.
2. I didn't think I would remember the name of the wad because it seem sort of random.
3. The levels were set mostly outdoors.
4. Plenty of ambushes and monsters however you always had just enough room to move around.
OT-Loving the graphics/colors of the forum BTW.
