EN WORLD DUNGEON: 16 months until 5e. Let's start building.

[Stoat]

Hundreds of feet below the surface world is a vast natural cavern, bordered by a subterranean ocean and ripe with giant mushrooms and phosphorescent growths. Thousands upon thousands of years ago, this dark realm was home to a kingdom of reptilian humanoids, the precursors to today's lizardmen and troglodytes. In life, their sorcerer-kings experimented with the weird energies of the underdark. In death, they were entombed in glowing ziggurats that hovered above the cavern floor.

Centuries later, an apocalyptic cult of giants learned of the inexplicable floating stone mined by the reptile people N'Auth. The giants bored a vast mine into the cavern and took what they found to make their floating castles. When their civilization ended, it left behind an enormous delve.

The giants were succeeded by their duergar vassals, who sealed off the lower deeps and mined gems and iron in the upper levels. The duergar were eventually taken by an inexplicable plague, and for a time the place was ruled by an exiled Devil, an unnamed Prince of Hell who served Levistus or Moloch (the record is unclear).

The Exiled Prince ruled for more than a century before he was slain, bound or driven away by a cabal of powerful clerics. The clerics built three sprawling complexes on the surface atop the site: one devoted to the god of the sun, one to the god of war and one to the god of knowledge. Over the decades, each complex developed its own cellars and dungeons.

Twenty-five years ago, the clerics of the god of knowledge dismissed all of their lay worshipers and descended en mass into the deeps. Their complex has been abandoned ever since.

Ten years ago, most of the clerics of the god of war departed to fight in a distant crusade. Only a handful remained behind.

Five years ago, plague struck the site, followed by monsters who boiled out from the depths. The clerics of the god of the sun and the remaining clerics of the god of war suffered grievous losses, but were able to retain control of their temple complexes.

Today, the clerics still control the surface. They claim a level or two below ground, but lack the manpower to truly enforce their claims.

 

[Celebrim]

I ran the LFGS's weekly open dungeon crawl for a while. I started out preping 5-10 room dungeons set inside mini-modules, but it took me about 20 hours of work to prep a 2-3 hour session. To reduce my work load, I started building a megadungeon using the 1e random dungeon generator to do the backbone work. Using this pattern, I was able to prep 10-20 hours of game play in the same time it had been taking me to do my more detailed/structured work, which let me easily keep ahead of the rate of exploration.

The dungeon started out as a planless sprawl, but eventually I morphed into the idea of having a 12 level dungeon. Each level contained one room in which there was a lock of some sort, although not every lock looked like one. The one of the first level was a circle of protective runes written in chalk in a hidden room. The one on the second level was an enormous grandfather clock. Each lock was gaurded, and each level also had a 'ruler' who desired most of all to open each lock. The players were told only that the dungeon was made by a mad wizard to hide a fantastic treasure in a vault at the bottom of the dungeon. I had eventually planned to theme lower levels by using different sorts of random generation.

Anyway, my suggestion is that if you really want to make a mega dungeon and have it work, you need to find 10-12 lead developers that will commit to making a level of the dungeon in a way that feels old school. Each dungeon should be limited to say 50-100 encounter locations, and each level should be planned to balance around a particular level of difficulty roughly 1-2 levels wide. Once the place is mapped and populated, if you have lots of support for the project the details can be drawn up by any one who wants to contribute to one of the teams. As lead developer, you should simply set a very broad theme that's easy to plan to, set some standards, and approve general plans (you'll probably want your own level to make as well). Prisons for extra planar beings and mad wizards are cliche, but they do help explain how anything is possible.

Honestly, the quality of work in mega dungeons is so low generally, that it wouldn't be too hard for an EnWorld fan project to meet or exceed the general level of quality associated with megadungeons.

 

[AbdulAlhazred]

I like the "the dungeon was built here because the location is special" concept. Back during the Dawn War the great primordial Tumultuous was brought to bay on this plain. As he was defeated the pieces of his body fell here and there about the plain, creating a range of low but steep and rocky hills and valleys. Once he was defeated the gods buried his heart, dropping a small mountain atop the spot in order to insure that it would stay safely buried.

Knowing that this location would retain dangerous energies and that the Tumultuous' servants would seek to tap into his remaining power here they built a small fortress on a flat spot near the peak of the mountain. They created a race of Nagas to guard the location. The Nagas built a temple to the gods and for many ages things were quiet.

Eventually, still many ages ago, the Nagas slowly became corrupted. Abandoning their original task and forsaking the gods they took up the worship of strange chaos beings, building a great ziggurat temple in the original fortress. At this time they began to delve, seeking access to the ancient power they had once guarded. For many centuries these creatures carried out terrible experiments and remade themselves into a race of snake-men, the Yuan-Ti. Their power spread and they created the most ancient empire known.

After many centuries the Yuan-Ti began to degenerate and were overthrown by an ancient alliance of dwarves and elves. The dwarves found the Yuan-Ti delves strangely attractive and began to dig and expand the original delves. Eventually they too were corrupted and fought a war with their former allies, the elves.

The elves eventually defeated the dwarves and the whole area became a vast forest realm. When humans first made their way into this area they carved out a few small towns and villages at the edges of the forest and traded with the elves.

Meanwhile the Necromancer Ugar found the ancient dwarven delves and reoccupied and cleared them. He rebuilt the ancient fortress and built a dark tower on the remains the Yuan-Ti ziggurat. From here he built an army of undead and conquered the forest, turning it into a vast dark shadow wood.

Ugar was eventually overthrown by a human hero and his evil faded, but the central part of the forest around the haunted peak remains an area of wilderness, dotted with the ruins of several ages and overlooked by the mountain itself. Several different adventurers, wizards, greedy dwarves, etc have tried to explore or occupy Haunted Peak Dungeon in the last century or so. While some of them have found fantastic treasures they have all eventually met bad ends. The local lord, Sir Rastamus built his castle near the head of the valley leading to the mountain, partly to guard against some tribes of goblins which make their lairs in the surrounding hills and forest. Now and then adventurers still set out from this castle, bound for Haunted Peak to seek their fortunes, or maybe for other darker purposes.

 

[Wycen]

This may be too early and I don't want to stifle creativity, but I plan to avoid WoTC Intellectual Property. I have no clue if 5E will even have a GSL, though I'm betting it wont.