I think if you're getting a dungeon from someone else it should be giving you something you can't do yourself, either because you are unable to do it or you don't have the time. This could be several things including ideas you might never have had or DM experience you don't yet have cooked into the design of the place. But I think the two most obvious are drudge work and art work. I'm not an artist so that's something I could get from someone else. And there are plenty of things that might be worth trying at the table but which take so much prep time you never get around to them. Let's think along those lines a bit.
The Maximalist Dungeon could have:
- Illustrations of every room. There's precedent with the image booklets in some of the TSR modules like Tomb of Horrors. I think a lot of those were produced because a trap needed visualization, but even just an illustration to show you the decay and layout of the rooms would be cool. As a kid I loved David Macaulay's Motel of the Mysteries and the detailed images of those rooms, in what was essentially a dungeon, unearthed.
- Illustrations of cluttered crime scenes. This is related to the above, because once you have high enough level of detail and once you have illustrations of every room, so that showing an illustration isn't a tip off of importance, you can hide clues in plain sight. Keys, notes, scraps of cloth. I have always been interested in solo play and I remember reading about (but never seeing) a solo gamebeook that had some full page illustrations for this kind of close examination/exploration. If you know what it was called let me know. Of course traps can become more brutal too, if the trip wires or pressure plates are right there in the picture.
- Illustrations of every monster, or at least every new monster. We are limited in our ability to imagine based on things we've seen before. But if you show us a picture your new monster can look like whatever you can draw. If you've followed my blog you know that I've tried to come up with new monsters through lots of different angles. This would be one I haven't tried: something hard to explain or describe but that you can easily understand by looking at a drawing. There could be all kinds of dreamlike, nightmarish, warped possibilities waiting for the right artist to unleash them on us.
- Portraits of every NPC. Without a face players don't have much to remember NPCs by, an accent, a cliched personality. Portraits could help with that. With portraits you could get a sense of class, wealth, general demeanor, scars, familial resemblance etc.
- Illustrations of treasure items. This is pretty simple, one way to make the +1 magic swords unique is to make them look different.
- So these have been about art so far how about the drudge work? Well, related to the NPC portraits above would be NPC personalities fleshed out for all the folks in the adventure/dungeon. I don't think I would personally need a whole backstory, because after a certain length I'm probably not going to read it. But if the background could inform how they act and make choices that would be cool to know. If the person was orphaned and has had to struggle alone they might not like the idea of accepting help, for example, and will become irritated if they can't pay for services.
- Along those lines, if we are dealing with factions, or politics, or romance, illustrated and annotated relationship webs of NPCs would be cool. What is the chain of command? Who will rumors spread to first? Who owes favors to whom? Who do you need to talk to find out intimate details about a particular NPC?
- And of course, going right along with the illustrations of treasure items would be unique treasure items with back stories.
- This is related to having detailed pictures of rooms but takes it one step farther. I've posted before about the idea of a grab bag store room, where everything in a room is on cards, so imagine if you combine a room's illustration, with small illustrated cards that you could hand players when they ask about particular objects or details. There comes a point where this would almost be better suited as a video game with items you can pick up and examine, a whole immersive digital world, but even in those, details are sparse or duplicated because of the work it takes to make things.
- Unique spellbooks is a subset of unique treasure items. And it doesn't have to be a cheesy facsimile, but having some illustration or physical card with the contents for each spell book found would be cool. And, of course, each would have unique spell variations.
- Give me a constructed language and a script or system of runes. I love this stuff, and I think it adds to the atmosphere in a game, but it takes so much time it falls by the way side in my games. But having even something that is little more that pig-latin for goblin inscriptions peppered around the dungeon that players can try and decipher would be fun. Or different aged scripts denoting excursions into a megadungeon at different times, that would be sweet. You want to talk about something that would be cool but I don't do just because of the amount of work, there it is.
- Along the lines of musing I did about sandboxes, it would be interesting to have the locations affected by different times of visit. So, maybe in the wet season this cave is half full of water and there are different creatures here, maybe during festivals this cult encampment has an entirely different population and feel to it. That is in essence asking for multiple modules. Yes. And players are likely to only ever encounter one of these states. Yes. But if you want maximal, that's maximal to me.
- Designer notes is something I don't think I've ever seen. Presumably, if you are selling a dungeon you have run multiple parties through it, multiple times. So, what did those folks do? What choices did they tend to make? I can see not wanting to read this stuff and experiencing my party's choices with them, but I can also see wanting to go back and read how that compares to the other folks that visited here. Designer notes would also be cool just to get a sense of what the maker was trying for and how this module/adventure fits in with their experience and other creations.
- DM notes would be slightly different. I'm thinking tips and advice gained through experience. So, this section of the dungeon is invisible, here's some ideas on how to run that at the table. This monster causes fear, here's a way you might handle what players under the fear power will do. Etc. Obviously this stuff isn't necessary to run a night of D&D, but if you are good enough and experienced enough at designing dungeons to sell me one, one of the assets you have is that experience. So why not share it with me?
So, yeah, I can envision a module that is a piece of art because of its elegance, how it gives you just what you need to run it and then gets out of your way. But I can also imagine a module that is a piece of art because of its ridiculous abundance, its richness that spills out at you like coins from a coffer.