how to make a megadungeon without really trying

So I've never found a commercially available megadungeon that really spoke to me, that made me say out loud "Yes! I want to spend the next fifty sessions running this bad boy again and again!"  There are lots of megadungeons out now with lots of good stuff in them, but I've not found one where the totality of it moved me to action.

In the nineties I tried solving this problem by using various random dungeon generators, like the one in the back of the first edition DMG.  That takes a long time for each level to be developed.  And doing this work helped me figure out a couple of things about my own approach to dungeon mastering:

• Although I have certain gut opinions about the aesthetics of dungeon maps and how they should be designed, I don't take much joy in drawing out levels myself.
• Ditto for stocking dungeon keys.  

I can looked at a finished dungeon level and key and form an opinion about whether a level is too crowded or sparse, whether the monsters work together, the flow of the passages, etc.  But building levels to conform with those ideas doesn't feel like fun.  It feels like homework.  So here's what I do instead,

Like many DMs, I own a lot of published dungeons.  And given the amount of free and cheap D&D material available on the interwebs, we all have access to approximately one gerjillion dungeons of various sizes and complexity.  My method now is to plunder that archive and assemble my megadungeon out of bits and pieces of other dungeons.

So, for example, you can take the first level of module B1 In Search of the Unknown, the moathouse dungeon from T1 The Village of Hommlet, the sample dungeon from Holmes Basic, and the same dungeon from the first edition DM and put 'em together like this: 

All I did here was drop some images of these maps into pixlr.com.  You can use Gimp or Adobe Illustrator.  The B1 map is a low ink version that someone on Dragonsfoot made many years ago.

I resized them all to roughly the same grid scale, no need to be super precise here.  Heck,you can see  I made a boo-boo moving the Zenopus dungeon from Holmes basic that I didn't bother to correct.  (This is a DMs working map, not art for public display.)  I looked for how to arrange these maps based upon where it would be easy to cut and paste a bit of corridor to connect them.  That's how you get from Quasqueton to the Abbey dungeon of the DMG to the Holmes dungeon.  

I rotated the Moathouse and used the paint tool to line up the Zenopus rat tunnels and the Moathouse ghoul warrens.  That's currently the only way the Moathouse dungeon is connected to the rest of the map.  If you don't want to brave Viet Cong style tunnel fighting against ghouls and giant rats, the only way to reach part of level 1 of this megadungeon is to exit and re-enter through the moathouse level entrance.  Or maybe there's an aquatic route.  I lined up the DMG and Holmes maps so that one can imagine the trickling stream of the DMG map flowing into the underground river of Holmes.  Maybe the giant crawdad pool in the Moathouse dungeon also connects to this underwater system.  Add some eggs to the crawdad lair and--if they are still there, say, ten sessions into the campaign--let those eggs hatch.  You can now see some places some young giant crayfish may migrate to in the dungeon.

That's the fun part for me, making connections between these disparate dungeon sections.  There are a lot of undead bumming about this new mega-level.  Are they all part of one necromantic scheme?  How do the berserkers in Quasqueton relate to the bandits under the Moathouse, or the smugglers under Zenopus?  Those are wildly more interesting questions to me than "What's in room 22?".  In this case, there's also the matter of the above ground structures mentions in the texts of dungeons.  Maybe the moathouse, the tower of Zenopus, the tower of Quasqueton, and the Abbey were part of a titantic sprawling fortified abbey that now lies largely in ruins on the surface.

You don't need any skill with graphics programs to use this method.  For the first level of the Vaults of Vyzor, I simply redrew the level maps on some big-ass graph paper:

Not pictured: Orange Lake (north of Citrine 1) and Purple 1 (south of Rose 1).
But this is the main section of level 1.

I got this 11"x14" graph paper (6 squares to an inch) at GaryCon II or III.  Black Blade Publishing was selling it.  Is Black Blade defunct?  Their website seems to have last been updated in 2010.  (UPDATE: Allen Grohe says Black Blade is still an ongoing operation.  Contact him or Jon Hershberger directly or visit https://www.facebook.com/BlackBladePublishing/.) You can get similar products from office supply stores, Amazon, etc.  Some day I'm going to get something like this and go real nerd crazy.

Anyway, if you look at these four levels smooshed together you'll see that there's only one corridor connecting each to the next one.  That was sufficient for 50 sessions of play, especially given that other connections existed in the lower levels.

You don't even need to go to the work of making a big map like this.  Levels 2 through 5 of Vyzor were never mapped out this way.  I just corridors leading off the page with a not "connects to room 24, page 7" or something like that.  You have to be careful annotate both ends of each connection and be mindful of the over all layout, but it totally works without the hassle of redrawing a bunch of maps.