Hello, hello! This time I set on a quest to port all mods with "mega" in the name. Surprisingly, there aren't many.
You thought we're through with Josh Mills? Think again! Mega Trainer Demo comes with no documentation as far as I can tell. A demo of what must have been a large vanilla mapset, it comes with 8 floors, which is still a considerable bite of gameplay. Mapping is focused on tight passages and long hallwas, but there's some open spaces in here too. You're also going to face a lot, and I mean A LOT of enemies.
Mega Wolfenstein 3-D by John Forester is an entirely different beast. With one exception, its five maps are all small and cramped. Not much can be said beyond that but... be careul where you're going, or you might get more than you bargained for.'