I really love the D&D in Space one page from the Blog of Holding. Spelljammer has always, to me, been an awesome idea executed poorly. Well maybe Spelljammer wasn’t poorly implemented, but its certainly not to my tastes. I like B/X for the most part, and really don’t like the MU nerfing nature of helms, on top of this the whole Arcane story arc is kind of a “telling other peoples stories” vs “Telling my stories” dichotomy. What I hope to outline is an interesting way to run Spelljammer like Space Fantasy “my way”. So how would I handle it?
First on the chopping block is the Platonic model of Chrystal Spheres floating in the Phlogiston. I wouldn’t do away with the Phlogiston, or Chrystal Spheres for that matter, rather I’d add to them. In my universe the Phlogiston is the nebular gas between places. Maybe the entirety of my Fantasy Space is the Phlogiston cloud, or maybe its just a galaxy (or a portion thereof) within a greater universe, but nonetheless, its not the only model. In order to facilitate things like Temple of the Frog, Expedition to the Barrier Peaks, and Tales of the Comet, Sci-Fi elements must occasionally appear in the floatsom of the phlogiston, additionally to facilitate worlds such as those found in Mutant Future, Thundarr the Barbarian, Kamandi, Metamorphosis Alpha, and Dragon Kings there need to be otherwise conventional systems awash in the weird (magic-like) radiation of the Phlogiston. So in my setting there are an array of crystal spheres and “free systems” (which are conventional solar systems wherein you can’t see the phlogiston due to solar radiation) throughout the Phlogiston.
Because AD&D elements work well with the Spelljammer system I’m thinking that the Core Rules would be Labyrinth Lord, Advanced Edition Companion, and D&D in Space. In addition I’d allow a wide array of character races and classes provided the player could provide not-insane BX/AEC rules for them, and a backstory from a system where their class/race/classrace makes sense. Also I’d take some of the Skyship/Voidship rules from Champions of Mystara, in addition Mystara would be contained within a “Prismatic Sphere” around which the crystal spheres of Greyspace, Realmspace, Knownspace(the Known World of LL), the Warden, Ebberonspace, and Krynnspace orbit.
Spelljammer helms screw over spell-casters, and generally suck. Also, spelljammer helms require the uninteresting railroady Arcane to work. Instead most ships are driven by Sails, Oars, and Turbines treated with alchemical substances that allow them to act on Aetheral or Phlogiston materials the same way nautical vessels work on wind and water. Vessels with demi-conventional sources of propulsion are faster than Solar Sails, they are much slower then Arcane/Divine/Psionic driven vessels which require no conventional propulsion (Sails/Oars/Turbines) and which can move much faster when needed. So generally the ship need only enchantments and crew, to go really fast (or to go without crew/convention) requires [Spell/Prayer/Mind/Faerie]Jamming.
Space travel is the general explanation for why fantasy worlds have variations on the same cast of characters, but these races form a family tree tied to stellar progenitors. Generally, for Demi-humans, there is a somewhat interlinked family tree. Humans, Dwarves, and Halflings are descended from the first starfaring race, elves and faekind are descended from the sidhe, a race of space-travelling shape-shifting vivimancers possibly descended from the Progenitors. Humans arose naturally, Dwarves arose from a slave race of subterranean miners who survived an apocalypse on some world in vaults, Halflings arose as humans bred as livestock (for human eating evil humanoids), the multitude of Elves and Fae arose as the Shapeshifting sidhe trapped in other forms at the end of their civilization. Some races, like Gnomes and Taddol, are the result of interbreeding (elfxdwarf and elfxettin respectively), and some races derive from another root entirely (like abolethes), but all races believe they come from the long lost homeworld(s), a world, or group of worlds, where similar lifeforms arose.
The gods worshipped by the many civilizations bathed in the phlogiston can be categorized as Elder Beings, True Gods, Immortals, and Lesser Gods. Elder Beings and True Gods predate or start at the beginning of the universe, they are worshiped in a variety of forms throughout the known universe, and can grant their worshippers spells anywhere. Immortals are once mortal beings who’ve attained godhood through fame, fortune, or popularity. An Immortal can only grant spells in their home sphere, or on their home planet in a Free System. Lesser gods are Elder Beings, True Gods, or Immortals who’ve fallen from grace, or beings born of the collective unconscious. Lesser Gods cannot have true clerics, only Witches and other lesser divine casters, and can only grant spells in those places in which they reside. Common faiths in the void focus on the worship of True Gods, or the archetypes Immortals ascribe to, and thus can gain spells anywhere, but divine casters who arose on worlds that haven’t made interstellar contact may lose their spells when they leave their worlds/spheres if they worship immortals or lesser gods.