Play Doom 2, map 32. Just do "idclev 32". There are two secrets: One is in the usual spot for the Grosse man, the other is in the same place on the opposite wall. "Use" the four end columns as well, and see what's under them. That might provide some ideas anyway.
I have. Honestly, I didn't think anyone would like to play a map like that. But if you guys do, that wouldn't be too hard. Of course, it'd be a Doom remake then