Looking at the module code XS2 you kind of know what you are getting yourself into here, it’s an Expert level Solo Adventure (you’d also know it’s the second of those). In this case you take a Dwarf character of D&D Expert level (the pre-rolled one being level 9) and with the use of pen paper and dice play through the adventure yourself.

If you don’t know, or don’t remember, Dwarf wasn’t just a race in first edition D&D, it was actually a character class on its own, which is why the adventure requires a Dwarven PC. The specific abilities of the Dwarf class are essential to navigate the labyrinthine mountain itself. By the end of the adventure you should have found and defeated the beastie on the cover, a Fyrsnaca which is stopping Dwarves from repopulating Thunderdelve Mountain, an almost mythical Dwarven paradise inside this mountain, even though at the start you are only out to save a Dwarven lady Champion kidnapped by bandits and taken to Thunderdelve.

A long (44 pages) and involved story, this is better than the average solo adventure, and one you should play if you think the idea is appealing. However, if you don’t enjoy solo play, there are also instructions here on how to make this into a full party adventure, so that’s some added value!