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XS2 Thunderdelve Mountain (Basic)

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The ancient dwarven kingdom of wonder and fable is no more! Only the tales of it's grandeur remain to entertain the children, or so you thought.

Then you met Nimron. Distraught and desperate, you alone can pass the gates sealed so long ago. Within are the lairs of bandits, cutthroats, and worse. The evil that destroyed the dwarven home - the Halls of Paradise - is awakened again. Into this horror ventured the dwarven princess Grona Marblefist to reclaim her kingdom. She, like so many others, has not returned.

Now you must face this peril alone.

Thunderdelve Mountain is a solitaire adventure for the DUNGEONS & DRAGONS Expert game. Players who don't wish to face the fallen Halls of Paradise alone may also use this adventure for group play

NOTE for Print Edition: Text cut off on right-hand side on pages 6, 8, 10, 12

Product History

XS2: "Thunderdelve Mountain" (1985), by William Carlson, is the last in a series of Solo adventures for '80s-era Basic D&D. It was published in September 1985.

About the Module Code. In 1984, TSR published BSOLO: "Ghost of Lion Castle" (1984) and XSOLO: "Lathan's Gold" (1984). The lack of a number in these module codes suggests that TSR was planning them as one-offs, not new product lines. Nonetheless, a year later TSR published a second SOLO adventure in the e"X"pert line. They could have named it XSOLO2, but instead decided to go with a shorter code that was more in line with the 1- and 2-digit module codes then being used. That's how "Thunderdelve Mountain" ended up being "XS2", even though there's no "XS1".

Origins (I): Back to the Basic Solos. Following the BSOLO and XSOLO releases, TSR had turned to a new solo-adventure technology: the "magic viewer". This was a red-tined piece of plastic that readers could use to access special paragraphs (and maps) without permanently alternating the product — as had been required by TSR's earlier "M"agic Marker technology (1983). CM5: "Mystery of the Snow Pearls" (1985) used a magic viewer, as did MV1: "Midnight on Dagger Alley" (1984), the only solo adventure for AD&D 1e.

Now, just a few months after the publication of "Snow Pearls", TSR decided to abandon their latest solo gimmick and to return to the basics: a roleplaying gamebook with clear text paragraphs that players could play again and again.

Origins (II): Back to the Classic Sources. "Thunderdelve Mountain" is very reminiscent of a certain classic fantasy source: when you put together a lost dwarven fortress and a dragon overlord … it's starting to feel a lot like The Hobbit (1937).

Origins (III): Onward to the Companion Rules. Though "Thunderdelve Mountain" returns to classic solos and a classic source, it was also on the cutting edge of D&D development. The adventure is about rescuing the hereditary descendent of the Keeper of the Forge of Thunderdelve. These Forges were the sacred relics of the dwarves, an idea introduced in the Companion Rules (1984).

The elves would get their own adventure focused on their own racial relic about five months later, in CM7: "The Tree of Life" (1986).

Adventure Tropes: Choose Your Own Adventures. Over the years, TSR offered a number of different takes on how to produce a solo gamebook, from the simplistic choose-your-own-adventure style of M1: "Blizzard Pass" (1983) to the numerous, complex game systems of XSOLO: "Lathan's Gold" (1984).

However, "Thunderdelve Mountain" is probably most like BSOLO: "Ghost of Lion Castle" (1984). Combat is just like in Basic D&D, while players are encouraged to fill in maps as they delve. Like "Lion Castle", this adventure is also dynamic, with players instructed to pencil in changes as they play.

The two biggest mechanical innovations of "Thundedelve Mountain" are a random treasure table and runic letters to be translated. "Thunderdelve Mountain" is also somewhat notable for its plot structure. It's organized as a series of quests: players must first rescue the Keeper, then find the Hammer of Vitroin, then slay the wyrm that's set up house in the dwarven ruins. It's a clever multi-part quest of a sort that's almost unknown in solo gamebooks.

Resurrected Races: Dwarves. "Thunderdelve Mountain" is a dwarf-only adventure. It was one of TSR's first strong racial focuses of this sort, though the dwarves previously got some nice attention in DL4: "Dragons of Desolation" (1984).

Exploring the Known World. "Thunderdelve Moutain" is one of the very few Basic D&D adventures that hasn't been officially placed in the Known World. However, "The Dwarves of Thunderdelve" by Demos Sachlas, which appears in Threshold #2 (2013), offers a theory. After examining the evolving maps of the Known World, Sachlas suggests that Thunderdelve lies at the end edge of the Cruth Mountains, between Darokin and the Five Shires.

Future History. Christopher Perkins turned this solo adventure into a multiplayer AD&D 2e adventure in "Dragon's Delve" for Dungeon #62 (November/December 1996).

About the Creators. Carlson wrote two modules for TSR in the mid '80s, the other being CN3: "Conan Triumphant" (1985), the final release for the Conan Role-Playing Game (1985).

About the Product Historian

The history of this product was researched and written by Shannon Appelcline, the editor-in-chief of RPGnet and the author of Designers & Dragons - a history of the roleplaying industry told one company at a time. Please feel free to mail corrections, comments, and additions to

We (Wizards) recognize that some of the legacy content available on this website does not reflect the values of the Dungeons & Dragons franchise today. Some older content may reflect ethnic, racial, and gender prejudice that were commonplace in American society at that time. These depictions were wrong then and are wrong today. This content is presented as it was originally created, because to do otherwise would be the same as claiming these prejudices never existed. Dungeons & Dragons teaches that diversity is a strength, and we strive to make our D&D products as welcoming and inclusive as possible. This part of our work will never end.

 Customers Who Bought this Title also Purchased
Reviews (1)
Discussions (5)
Customer avatar
Peter W February 29, 2024 8:08 pm UTC
Anyone know if the following from the descrption is still valid: "Print Edition: Text cut off on right-hand side on pages 6, 8, 10, 12"?
Customer avatar
David F July 18, 2022 10:42 am UTC
POD! There are no issues with magic markers or special printing needed, so a POD would be ideal.
Customer avatar
Johnathan D May 12, 2022 7:51 pm UTC
POD please
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Daniel R February 11, 2022 8:09 pm UTC
POD please
Customer avatar
Nathan B August 14, 2017 2:28 pm UTC
The listed Edition for this is wrong should be Basic/Expert not oD&D
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