Spelljammer: AD&D Adventures in Space is a guilty pleasure of mine. Written and conceived by Jeff Grubb, this overstuffed boxed set was first released in 1989, just as I was transferring between two colleges. For a lot of reasons, this was a very tumultuous time in my life and, as a result, my memories of it are very vivid, even thirty-five years later – memories that include purchasing Spelljammer from a Waldenbooks in a suburban mall and then poring over its contents for some time afterwards.
As its subtitle suggests, Spelljammer took AD&D 2e into "space," though not in the traditional scientific (or even science fictional) sense of the word. Rather, Grubb took inspiration from ancient and medieval conceptions of the cosmos, in which the stars and planets are embedded within celestial spheres made of ether. Rather than multiple nested spheres containing all the celestial bodies of a single solar system, as the ancients conceived, Grubb imagined each sphere as encompassing an entire solar system or, more to the point, an entire campaign setting, with all the spheres floating within a "sea" of flammable material called phlogiston.
Through the use of flying vessels equipped with magical "helms," it was possible for the inhabitants of worlds within one sphere to journey to worlds within another. This was the high concept of Spelljammer: the ability to travel between TSR's various campaign settings by means of magical "space" ships. It's a very clever conceit, one reminiscent not just of ancient cosmology but also of Jack Vance's Rhialto the Marvelous. In addition to facilitating transit between existing settings, Spelljammer also opened up the development of a "bridge" setting between them, namely, the larger cosmos of races, organizations, and even worlds that make regular use of space travel.
In some respects, Spelljammer is the forerunner of both Ravenloft: Realm of Terror (1990) and Planescape (1994), two other TSR boxed campaign settings whose conceptual frameworks allowed characters from Greyhawk, the Forgotten Realms, Krynn, and elsewhere to adventure side by side while also exploring entirely new locales created to flesh out the bridge setting. In the case of Spelljammer, that bridge setting includes a mix of the good, the bad, and the downright weird. There's the pompous Elven Navy attempting to keep the peace, xenophobic beholders at war with themselves and everyone else, mysterious mind flayers with their nautilus ships, the spider-like neogi, and mercantile arcane, just to name a few. As presented in Spelljammer, the cosmos was positively filled with all manner of space-faring peoples – and an equally large number of space-based locales and mysteries.
Chief among these mysteries is the titular Spelljammer, an ancient – and gigantic – manta ray-shaped space vessel with an equally gigantic citadel on its back. The origins and true nature of the Spelljammer are unknown, making it the subject of many legends. It's also the destination of many a spacefaring adventurer, as the citadel on its back is reputed to hold untold magic and wealth for those bold enough to venture within. The Spelljammer is thus equal parts the Flying Dutchman of space and an old school megadungeon, which is itself a pretty good high concept.
Of course, Spelljammer was replete with high concepts – and that's part of the problem. In an effort to be expansive and easy to use to use with any existing AD&D campaign setting, Spelljammer is something of a curate's egg. I suspect that this was due less to Jeff Grubb's own preferences and more to directives from TSR regarding the boxed set's place within their larger publishing scheme. This prevents the bridge setting from having a strong flavor of its own, which is too bad, because it contains a lot of elements that I wish had been better (or differently) developed. Instead, the whole thing has a kind of underdone quality that fails to do full justice something I still consider to be a great idea to this day.
Spelljammer straddles the line between the end of the Silver Age and the beginning of the Bronze Age of Dungeons & Dragons, which, I think, explains a lot. Like the products of the Silver Age, Spelljammer is an exemplar of the era's "fantastic realism," itself a metastasis of Gygaxian Naturalism. At the same time, Spelljammer heralds the start of AD&D's "boxed set era," when TSR cranked out new boxed campaign settings (and expansions thereof) almost on a monthly basis – a seemingly never-ending parade of good ideas not given sufficient time to germinate. There's reason why so many gamers of a certain age have such affection for this period of AD&D's development. For all of the flaws in their output, almost all of these boxed sets contained good, imaginative ideas that inspired a lot of us, Spelljammer included.