Super-Dungeons

A big part of being a DM is making sure the players are enjoying the game, if for no other reason than if the players aren't enjoying the game they're likely to stop playing.

So as DM it's important to know your players and what they want to do and build accordingly, or at least be upfront with what type of campaign you're intending to run. Super-Dungeons tend to lend themselves more to the murder-hobo type players, so coming up with big elaborate plot lines is likely going to be see and as many words between the player's sword and the next monster to fight. Alternatively you could end up with a bunch of players who want to Splinter Cell the whole dungeon and sneak their way through everything.

Plus as a DM you have the luxury of seeing everything, while the players only see what you show them. You don't have to have the dungeon done when the players start, you can build enough for a session or two, drop them in, see how they play, and then build the next chunk accordingly.

Plus, you never know what players are going to latch onto. You could have an NPC that they grow fond of, or latch onto a throw-away piece of fluff or some odd detail. For example, in a session last night with my players they found a few books in an abandoned campsite. They were simply logs, but no one present could read the language they were written in. However, one player recognized the language as the same one the evil cult country used and got super nervous. Another player (who is an idiot) got super obsessed with the books and started demanding them. A third player (who plays an idiot) then jumped to the conclusion the books were cursed and had possessed player 2. None of them knew they were just travel logs, so I can use them as hooks later on for curse shenanigans. If they were doing a super-dungeon, that could easily lead them dealing with a bunch of evil wizards in the next batch of rooms who want their tomes of power back.

I guess I would make it a sort of excavation process, where new wings open up after some digging and the players explore it during a session. Would take a little work on the denizens end though because you have to justify monsters showing up in a sealed off complex.

Yes, but the players get to decide what they do about what's in the dungeon. That's where the story comes from.

>. Super-Dungeons tend to lend themselves more to the murder-hobo type players
Muderhobos are as old as the hobby, but this is actually not true in early editions. For one, killing things as impulse is often EXTREMELY dangerous given how weak characters are to start with. Second, it's not even particularly well-rewarded when you take in mind how likely it is that you're going to die in any given fight. Killing monsters gives a pitiful amount of XP, even more so when compared to the unimaginably larger amount you could get by playing it smart and taking their gold without blood

By contrast, in modern editions, characters can ONLY grow in level by killing things, with the other methods of advancement if any usually being minor variant rules

By adapting/stealing 13th Age's Eyes of thr Stone Thief. It's a living dungeon that pops up out of the ground, devours cities and people, and goes back under. Inside is a fuckhuge ecosystem with safe havens that just happen to not compress when it dives, monsters who symbiotically live within the dungeon, also its semi-sapient. It's meant to eat up literally half of a 1st to 10th level game, from about third or fourth all the way to seventh or eighth. In a game with only ten levels.

>By contrast, in modern editions, characters can ONLY grow in level by killing things, with the other methods of advancement if any usually being minor variant rules
Both 4th edition and 5th edition, in their main discussion of experience points in the Dungeon Master's Guide, explicitly award XP for overcoming risky encounters, regardless of whether the process of overcoming it involved killing monsters.

Yes, but at least for 5e, the game is not really built to handle that. The CR system is even more useless that it already is if your players are keen on taking non-combat solutions whenever possible, given its base assumption is that the party is going to be spending a lot of resources fighting monsters, and like half the classes are combat machines

>some old TSR modules like Keep on the Borderlands

There's several iterations of this from OD&D, AD&D, 3e, and possibly even later.
I'm a big fan of Hackmaster's Frandor's Keep which is basically an updated and really polished version, though it cut the Caves of Chaos so you'd need to use one of the other older versions if you want that.

Check Dungeon Meshi.

I have thought Borges Library of Babel would make for a fun and messed up dungeon.

libraryofbabel.info

Write your own program to generate it randomly.

Honestly i'd be tempted to go full jrpg with it.

There's a dungeon in the middle of the city, created when a mad wizard decided that he wanted to make a 'reverse wizards tower' back when the elves and dwarves were still young races.
Each floor has a different biome filled with different creatures that would live in said biome. No one knows how many floors there are but the sign carved into the first door says untold treasure and power awaits those who can beat the dungeon.

The city has taken to using the dungeon as a great deal many things. Such as for boosting tourism by taking people on 'safari' through the relatively safer floors. Training the guards in how to handle a large variety of creatures and magic. An engine for the town economics because of all the rare monster materials that can be harvested. And of course a place to throw criminals who've committed the most heinous of deeds.

But with all the benefits the dungeon brings it also means that lots of people are going to be flooding into the city to try their hand at wealth, meaning someone has to try to organize this shit, be around to buy and sell the treasures found by adventurers, and just in general lots and lots of room for intrigue based on which family/company/whatever is in control of the dungeon entrance at any given point.

Someone already suggested this here.
Dungeon Meshi is GOAT, I've borrowed a lot of ideas from it in my own game.