There is a certain type of adventure that in recent years seems to have fallen out of popularity: dungeons.
"I Look Up!"
The release of several old D&D modules got me looking at some of these old original adventures, and they are quite eye-opening on the subject of dungeon design. These are the first games of D&D we played and while some are a little dated, it's easy to see why they kept us playing. While almost everything in those adventures was dangerous, there was magic and mystery in the rooms you found. There were rooms with strange orbs suspended from the ceiling; mysterious indoor gardens full of medicinal plants, poison and monsters; ghostly feasts that share a tragic history; and mysterious keys guarded with fiendish traps.
I think I know why dungeons fell out of vogue. Way back in the early 80s we discovered city adventuring. Modules then became quests or investigations across a cityscape full of NPCs and role-play opportunities with all manner of details and cultures. This new way of gaming outside a maze opened a whole new sandbox. This change in adventure design opened new vistas for adventurers, but crowded out the traditional dungeon crawl as a result.
A Return to Form
Luckily, in recent years we have seen a more interesting return to dungeons. More designers are coming back to them and trying to break the myth. Mork Borg has its share and a other ‘old school’ games have sought to blow the dust off the idea of raiding underground facilities. Its fun to dive into these lairs once again, and a simple diversion from what has become the usual kind of game. While I’m certainly more on the side of narrative play and character interaction, sometimes it is nice to know that you just need to pick a door rather than work out the villain’s plot and craft an elegant plan (that one of the players may just ignore anyway).
If you are thinking of crafting a dungeon of your own, here's a few pointers.
Give the Place A Reason
Whether it is an old ruin or an underground laboratory,
make sure the dungeon has a reason to exist and some sort of history. A hole in the ground isn’t very interesting so give it a back-story, even just a small one. It might be a tomb, an old ruin creatures have taken over or a lab where magic went wrong. It need not be especially clever, just as long as you can place it in your setting.
A Dungeon Need Not Be an Actual Dungeon
What you are creating is a place full of rooms linked with doors and corridors, so
it need not be underground. A house or a castle is basically the same, as is a sky city, large airship, underwater citadel or even a walled in town (put a roof on real world Venice and you have an epic dungeon).
Don’t Construct It with Only One Path
When you are making a lot of cool stuff it is very tempting to make sure none of it gets missed. But you should
avoid the temptation for having only one path through the dungeon that takes in every room. If the player characters miss out rooms 34-48, you can use them in the next adventure. Nothing is wasted. But if you insist they follow one path you are ruining the fun of exploring a dungeon and taking away the agency of choice. If you offer several different paths, when they enter the room of certain death you can point out with a clear conscience that they didn’t have to open the black door with the skull on the front.
Corridors Are Rooms Too
Don’t reserve encounters just for rooms. They can happen anywhere in the dungeon, in corridors, on stairwells; anywhere the player characters don’t expect one.
Add Some Mystery Not Just Monsters
While you will need a few monsters to fight to gain some treasure,
put in traps and just weird stuff too. Not everything need be deadly, just something weird to make the player characters think can be fun too, if only to cross a room (
the Crystal Maze will be a big help here). With magic in the world you can put some very odd places in a dungeon. Just imagine something that would look strange and enticing when they open the door and then figure out what it does. It might be a room full of glass spheres, a garden with odd looking plants, a table set for a feast with only statues as guests. The weirder the room the more the player characters will be intrigued.
Make Sure There Are A Variety of Encounters
This relates to the above;
don’t rely on one sort of encounter. Make sure you have a mixture of traps, monsters, weird rooms and role play encounters. Try to avoid having the same type of room twice in a row if you can.
Don’t Skimp on the Role-Play
Even dragons might chat;
just because it is a dungeon doesn't mean there are opportunities to role play. Trapped creatures, intelligent monsters under a curse or a contract and even the odd guard might be talked to as easily as fought. You can let the player character make this decision, by who they choose to attack on sight. But remind them that they can talk their way out of situations as well.
Make Every Door Worth Opening
If you do the job right,
each door the player characters come across will fill them with a mixture of fear and anticipation. What lies beyond this door, a trap, a fearful death, untold riches or wild magic? If a room or encounter doesn’t’ feel that interesting to you, cut it from your dungeon. Maybe consider it a little and use it later on when you’ve made it work better. A dungeon need not be a sprawl, and a shorter one has the advantage of potentially allowing the player characters to escape and try another one some other day.
And UR-dms have to be designers. I wish you luck while engaging pre-made philosophies these days, the borrowed rather than forged. 
