More Mega-Dungeon Meanderings (and on a Monday!)

I've been hanging out in reddit a lot more over the past few years, among its OSR, AD&D, Greyhawk, mega-dungeon, miniatures, and related old-school (and Delta Green) communities. 

 In /osr/ the user livefreebugs posted a question at  https://www.reddit.com/r/osr/comments/wzugz6/what_elements_would_make_your_ideal_megadungeon/ asking (with my linebreak additions), 

I've been reading a lot of theory and perform advice on megadungeons and it seems like an area that there's a lot of room for awesome new adventures in. There's definitely a‍ risk some megadungeons run into of being repetitive or incoherent and having a huge quantity of locations over consistent quality. I think vibrant factions, multiple approaches, verticality, a sense of place/history that gives deep interconnections between areas of the dungeon, and a scale that allows for many sessions of return delves. 

I know it's not too controversial here but while not exactly "mega" depending on your definition I think the Caverns of Thracia is one of the better large dungeons ever made due to the integration of layout, history, occupants, into the whole and not feeling like a jumble of random rooms (though gonzo funhouses' can be sweet too). 

What would you look for in your perfect large/mega-dungeon that doesn't exist yet?

My response follows. 

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My favorite things to do in mega-dungeons, as a player or DM:

• Explore...:  lots of room to wander around, get lost, find cool things no one else has found, pass through empty rooms/chambers/halls on the way to fun encounters!  A mega-dungeon must also lead outward into the world(s), as well as pull the world into it's orbit from time-to-time
• ....and Map!:  I love to map while playing and mega-dungeons provide wonderful opportunities to do so :D
• Interact with Interesting characters:  whether PCs or NPCs, some of whom are only available to meet in the mega-dungeon, of course!  Over time, they may offer opportunities to ally, to cautiously negotiate with neutrally, or to become bitter foes (long- or short-term).  Either way, they are the personalities that help to bring the mega-dungeon to life, and they 're not just factions (although they're important too).
• Encounter Tricks, Traps, Trials, and Enigmas!:  any adventure should not just be about combat, and the rest of the challenges should include aspects that bring the environment into the foreground from time-to-time
• Magic!:  there should be cool, fun magic items, spells, effects, and other artifacts and relics that are only available in the mega-dungeon---and some should be permanent features that the players may want to return to for years on end (rather than the usual kind that are hauled up and out and used/sold)

Mega-dungeons sometimes have overarching themes that range in from obvious (Rappan Athuk) to more-subtle (Caverns of Thracia), while others don't seem to have themes at all.  I like there to be zones with and without theme, to keep the whole from getting stale, and to allow the DM freedom and flexibility to design "off topic" levels, or players to really dig deep into side-levels, sub-levels, and extra-planar environs that catch their eye.

Some additional thoughts at https://grodog.blogspot.com/2020/06/grodog-favorite-mega-dungeons.html and in my review of Castle Zagyg at http://greyhawkonline.com/grodog/gh_castle.html

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What are your favorite aspects of gaming in mega-dungeons---the things that bring you back to the table again and again?

Allan.