There was a blog post a few months ago that made an attempt at listing them.

https://darkangel866.blogspot.com/2017/04/megadungeon-list.html?m=0

FWIW, even though I love dungeons, I haven't really seen a published megadungeon I like.  I think published versions suffer from lack of playtesting and artificiality (RA's small 8.5x11 levels, stonehell's rigid shapes) while organic ones suffer from the effort required to bring order from the chaos of play notes.  I'd say the best known megadungeons I've played in are unpublished, such as Allan Grohe's personal take on Castle GH, Chainsaw's Foolsgrave, and a couple of other guys.

I do like Barrowmaze as a massive themed dungeon.  But I need the vertical dimension to be a true megadungeon - falling into a big mess is inseparable from megadungeon, for me.  But I wouldn't hesitate to use Barrowmaze (and I do own it).

The other thing that I pre-load into the megadungeon isn't the size, but the mythic underworld concept.  If it isn't a mythic underworld, I'm not interested in exploring what is just an endless series of lairs in a tunnel.

Would Parlainth for Earthdawn count?
I've only played it, never read or ran... but it seemed huge and weird, and had a strong bit of story running through it. True, it's actually a ruined city with catacombs beneath... so I'm not sure the open air bits count.

I would say Dwimmermount by far.

Firstly, it's actually fleshed out thanks to the job Autarch did.  A lot of megadungeons are pretty sketchy.  Stonehell is great, but it used a modified 1 page dungeon format so by design it's somewhat sketchy.

Secondly, despite all the crap about the 2000 coppers and giant rats, it's got a lot of interesting stuff. Martians, Venusians, Jubilex in a canister like Prince of Darkness

Thirdly, again, thanks to the job Autarch did, it's very playable. Castle Whiterock may or may not be a great megadungeon, but it's a pain in the ass to read, much less run.

Quote from: S'mon;997793Thinking about stuff like Dwimmermount, Stonehell, Castle of the Mad Archmage, Barrowmaze, TSR Greyhawk Ruins, Rappan Athuk et al. What are your favourites and why?

I think that for me it really varies, based on who I've been playing (or sometimes, working) with.  I've really enjoyed nearly all of the mega-dungeons that I've played in or run*, but I've also generally had the wonderful pleasure of excellent DMs and players, which makes all the difference in the world in terms of the game experience at the table.

Thinking through the mega-dungeons I'm familiar with, some stand outs that still stick with me are:
- best mapping environment to explore:  Castle El Raja Key, Maure Castle, Caverns of Thracia, Foolsgrave
- most-fun encounters:  Castle Greyhawk, Foolsgrave
- most-fun enigmas/centerpieces:  Castle Greyhawk, Maure Castle, WG5, ASE1/2-3, Undermountain
- coolest and biggest maps:  Castle of the Mad Archmage, The Quilt Map, Undermountain, Vladikavkaz, Arden Vul, Foolsgrave
- pulls it all together fabulously:  Caverns of Thracia, Maure Castle, Tomb of Abysthor

In terms of best-published format/presentation for a mega-dungeon, I don't think that we've seen that yet.  Necromancer Games build out a good standard template for dungeon levels between Rappan Athuk and Tomb of Abysthor, and The Grand Temple of Jing attempted to design a new layout format for the mega-dungeon (similar to what Ptolus successfully achieved for the city sourcebook), but neither product quite achieved their overall goal on those fronts, due to other, over-shadowing issues with the products (horrible maps in RA the first go-round, while the KS version of GToJ didn't really pursue the usability goals of the first version of the dungeon).  A well-built layout focused on at-the-table usability, married to a brilliant  book design could really distinguish a future mega-dungeon product, and potentially allow it to leapfrog into the top of the list....

Allan.

* Mega-dungeons I've played in:
- Castle El Raja Key - written and DM'd by Rob Kuntz (pre-published version)
- Caverns of Thracia - written by Jennell Jaquays, DM'd by Jon Hershberger
- Dark Tower - written by Jennell Jaquays, DM'd by Jon Hershberger
- Foolsgrave - written and DM'd by Chainsaw (pre-published version)
- Jakallan Underworld - written by Phil Barker, DM'd by Victor Raymond (pre-published version)
- Thieves Fortress Badabaskor - written by Bob Bledsaw & Mark Summerlott, DM'd by Jon Hershberger

Mega-dungeons I've run:
- Castle Greyhawk/The Lair of Thelmon Onvalth - my own (pre-published version)
- Castle Greyhawk - EGG and RJK - Bottle City, EX1-2, WG6, etc., etc.
- Castle El Raja Key/Maure Castle - RJK - WG5, The Statuary, Chambers of Antiquities, Warlock's Walk
- Mythrus Tower - Matt Finch
- Tomb of Abysthor - Clark Peterson and Bill Webb  
- Undermountain - Ed Greenwood - Box set 1, Dragon articles

Mega-dungeons I've designed, developed, edited, and/or published:
- Castle Greyhawk/The Lair of Thelmon Onvalth - my version of Castle Greyhawk, including my version of The Black Reservoir (based on EGG story vs. RJK level) and The Quilt Map (based on Tony Rosten's map)
- Castle Greyhawk - RJK - Bottle City
- Castle of the Mad Archmage - Joe Bloch
- Maure Castle - RJK - Warlock's Walk
- The Twisting Stair centerfold mega-dungeon - Tony Rosten

Mega-dungeons I've read but neither run nor played in:
- Anomalous Subsurface Environment - Patrick Wetmore - Levels 1 and 2-3
- Arden Vul - Rick Barton (pre-published version)
- Barrowmaze - Greg Gillespie (first versions, pre-expansion via Barrowmaze Complete)
- Castle Blackmoor - First Fantasy Campaign and the 3.x version
- Castle Greyhawk - Castle Zagyg, WG7, WGR1, Expedition to the Ruins of Greyhawk, etc., etc.
- The Darkness Beneath - a few levels in Fight On!
- Dwimmermount - James Malizewski
- The Grande Temple of Jing - Danny O'Neill & Diverse Hands
- Mines of Khumar - Stefan Poag
- Palace of the Vampire Queen - Pete & Judy Kerestan
- Rappan Athuk - Clark Peterson & Bill Webb - R1-3, Rappan Athuk boxed set (original)
- Ruins of Kwalishar - Tim Kask (pre-published version)
- Stonehell - Michael Curtis - Vol 1: Down Night-Haunted Halls
- Undermountain - Ed Greenwood & Diverse Hands - Box set 2, the Fireplace level (Dungeon Magazine), a smattering of modules too
- Vladikavkaz - Keith Sloan (pre-published version)

Quote from: JeremyR;997976Thirdly, again, thanks to the job Autarch did, it's very playable. Castle Whiterock may or may not be a great megadungeon, but it's a pain in the ass to read, much less run.

Yes that was my impression from looking at the two rather briefly - Whiterock I found hard to read & grok, Dwimmermount seems presented very well. My only real problem with Dwimmermount is that it looks hard to genericise; it seems tied to the setting that developed around it. Normally I like megadungeons I can just plop into a campaign setting such as Wilderlands, for which the short format of Stonehell & Dyson's Delve works very well. But I'm definitely considering running a Dwimmermount campaign - I accidentally bought the hardback ACKS version despite not having ACKS, might run it in Swords & Wizardry, in 1e/OSRIC or in 5e - not sure.

I found Caverns of Thracia (I used 3e version) never grabbed my group as a place to explore for its own sake. I think the paucity of treasure was a big part of that, along with the high threat level. Also it has no low-level safer areas, instead it has dangerous & deadly. It worked well for a high level delve where PCs went in to destroy the awakening First King before he could get up & start causing trouble; but no desire to keep exploring. By contrast they were always keen on exploring Dyson's Delve - lots of treasure, few screw-you areas, and frequent access to lower levels, were three factors.

Quote from: grodog;998016- Arden Vul - Rick Barton (pre-published version)

Wow - Rick and Joe B. dropped a teaser map because it looks like this is in the publishing pipeline, and it looks absolutely amazing.

http://knights-n-knaves.com/phpbb3/viewtopic.php?p=236014#p236014

That does look pretty sweet.

Of the list above? Barrowmaze.

Quote from: RPGPundit;999219Of the list above? Barrowmaze.

Is it worth the $75 for the hardcover?

Quote from: S'mon;999245Is it worth the $75 for the hardcover?

I guess it mainly depends on whether you're going to run it or not.

I just had Forbidden Caverns of Archaia delivered to my house. I won't blather about it before I've read it through in detail, but thumbing through and giving it a sniff it looks very promising. It has been described as Keep on the Borderlands re-imagined as a megadungeon, and that is a pretty accurate tag line. But it is really fucking big - you could seriously play years of a very active campaign in this place. The total size must be close to 50x that of a common, tournament-scale dungeon. And it has a lot of moving parts and diversity in locales and challenges. I'll report back in a day or two when I've had a chance to really read it.

I heard they shipped.  Still waiting to get Archaia.  I have the pdf, but haven't downloaded it yet, wanted to read the book.

It's really good; I'm still only about 1/3 through it and will need a couple of days to look over the rest, but its clearly one of the better big dungeons. It is broadly similar in scale to Rappan Athuk, and there are similarities between the two in terms of structure (i.e., a huge number of small to medium levels rather than a few gigantic levels, like Undermountain), but the layout is very different - think Caves of Chaos on massive doses of growth hormone. The content is divided more or less evenly into three parts: complexes that are homes to war bands of humanoids (orcs, gnolls, etc.), lairs and crypts containing a small number of weird and dangerous things, and a big complex that reminds me a bit of G3 (halls of the fire giant king). I like the fact that 1st level characters could try their hand at this environment, provided they kept their wits about them and recognized when they were getting in over their heads, but a higher level party (say, 7th-10th) could also get into hot water pretty easily. I'll have more to say by the weekend...

I am running Stonehell now, and I found it very easy to drop into my campaign and both easily adaptable (using DCCRPG and my own post apocalyptic setting) and extensible. Score it on one of Lulu's very occasional 40% off deals and you get a lot of fun at a very reasonable price.