There must be.Wait, is there a Gnome out there?
I'm thinking of running this soon...While it's not quite large enough to be called a mega dungeon, Bittermold Keep (Cursed Scrolls #1) took my group the better part of five 4-hour sessions to finally explore all of it. They loved coming back each time and seeing how it had changed, as we play (roughly) in real time between sessions. Start and end each session in a safe haven (usually Wardenwood).
No special rules needed. They went through a lot of torches!
SD is a great fit for a open table dungeon crawling game.
I just ordered two Chessex Megamats and going to draw out the entire dungeon.
I love UDT. You can get some pre-made on Etsy if you don't want to craft your own. Professor DM really should have trademarked that.But an approach I've been toying with in my mind for a couple of years is to use Ultimate Dungeon Terrain or something similar with modular wall pieces to lay out the immediate area around the PCs at any given time, but make them map or memorize if they want to have the larger map. This can work both in person or online if I just keep a separate camera pointed at the UDT. Either approach allows me to use my miniatures collection and is quick for setup and takedown, and more space-efficient than a 4x6 megamat while still supporting larger dungeons.
That's part of why my preference is still for the original gridded UDT, rather than the later zoned UDT.I love UDT. You can get some pre-made on Etsy if you don't want to craft your own. Professor DM really should have trademarked that.
The only "flaw" I can see with UDT is the explicit centering of one space. This prevents multiple simultaneous fights...unless you have two UDT and sundry props. So things like fights on both ends of a long room. Fights on either side or a chasm. Etc.