As to how we would go about the project, the first thing I would want to do is have a wide-ranging discussion about the themes we're interested in, and decide on some very basic features of the world, such as the roles of magic, technology, and science; which races are most common; the existence and nature of gods/immortals, other planes, and other cosmological features; and so on. At the same time we would come up with a world map (likely through trial and error) that we all liked enough to agree on. Once these things were done, we could move on to developing the world, probably in a Gazetteer-like fashion, with teams working on each area - although since this would all be done on a forum, anyone could contribute wherever they liked too.
Just as I think the emblematic elements of Spelljammer should be removed (from any Creative Commons Fantasy RPG Space rules*) I also think that "Immortals" (at least as Mystara uses them) should probably be something you don't touch with a barge pole. Immortals are just too "stereotypical" of Mystara.
* = I know you said you were thinking of a systemless world, but from a space, point of view, you need to talk about things like air, gravity, travel times and that sort of logistical stuff. Those sort of things, and even things like how big the sun is are "rules of nature" and they would change the way that some parts of the game would play.
Having said that, I think it would be great to have "immortality" within the game and make it possible for mortals to become "immortal". I think we could also have the "elves are immortal" thing that many people expect, but do that properly
(i.e. don't say: "they are immortal, but eventually get this urge to sail off to another land and live with the elven gods" - if you say that, you might as well kill them and have an elven heaven).
I also think that it might be OK to allow mortals to become godlike beings (which might normally take so long that they need to become immortal before they can gain godlike powers).
One thing I've been wanting to see someone do for a while, was a set of OGL pantheons of gods. But if this project got off the grounds, I'd change that wish to a set of "open content" pantheons of gods. I would like to see someone (or a group) study a specific culture, create a RPG model of their deities, cosmology myths and other important cultural/religious elements and then turn that into something that could be reused by other people.
And I would like to see the material published separately under the Creative Commons licence, the OGL, and any other RPG licence.
By this I mean that people playing with the 3rd edition rules (or other OGL systems like Pathfinder) could have an "Egyptian SRD", a "Polynesian SRD", a "Roman SRD", a "Viking SRD" (or whatever) that took the religious parts of that culture and explained it in Open Game Content terms. But at the same time, people playing with totally different open RPG systems could build an Egyptian, Polynesian, Roman, Viking or whatever version of their game.
Now, if you had those building blocks (and you wouldn't need to build all of them in one go, or even commit to finishing them all yourself) you could then have a "Thorf's World" and decide that the god "Pan" is worshipped on Example Island and people would have something to refer back to to know what you
meant when you said Pan.
But - at the same time - if you republished these building blocks as things like a "Chinese SRD", an "Atlantis SRD", an "Arabian SRD" or whatever, you could actually use WotC's own SRD, to create a D&D compatible game (albiet only compatible with 3rd edition) that (like the original SRD that WotC published) can never
be "cancelled" because they have been published under a "we can't take this back" licence.
I think you would eventually want to build on these things taken from the public domain parts of our culture (and create some things that only exist in Thorf's World) but the generic things really belong to the world, so I'd love to see a project that systematically creates open source RPG versions of our cultural heritage.
I'm sure that a raw version of this cultural stuff isn't what you would want to put into Thorf's World, but if you want to have one country that is "a bit like a mediaeval European country" and another country that is "a bit like anchent Greece" and a third country that is "a bit like an oriental country" you would probably be doing much of this sort of R&D anyway. You might even be going as far as looking for the layout of a typical African village or a typical Vietnamese temple or the sort of weapons that were common during the Bronze Age. So why not also offer that R&D separately. Something like that could allow people to build other worlds (or other countries on your world) that come up to the same sort of standards as Thorf's World.
As for cosmology, I think that depends on culture. I think that if you look at the sort of culture you might want to import onto your world, you can see if your cosmology should include an "Otherworld" or an "Afterlife" or "Mount Olympus" or whatever. I would say that rather than something like The Great Wheel, where you have a fixed number of outer planes, you could allow new pantheons to "bolt onto the cosmological system" in whatever way is most logical for that culture. So if a culture, like the Aztec culture, says that "the gods live in space" you create a planet full of Aztec gods and if another culture, like the Greek culture, says that "the gods live at the top of a mountain", you create a mountain full of Greek gods. These places could still be on another plane, but the way to get to the Greek "outer plane" could be a portal on a mountain top and the way to get to the Aztec "outer plane" could be to find a portal on an asteroid (or whatever works for that culture).
Planescape (as D&D describes it) wouldn't work, but we could still have dead people (and maybe living people) who live with the gods and find a way to travel from the realm of one god to the realm of another god.
Personally, I would downplay the cosmology, because avoiding having one would allow people to bolt "Thorf's World" onto a D&D campaign world or make it a port of call in a Spelljammer or Planescape game. But if you treat cosmology as a "building block" element, you can make an optional
"Fantasy Cosmology" supplement that can be used for "Thorf's World" or any other RPG
. You could actually make something that replaces Planescape as the way to connect different worlds. And if you made other planes that had a mythological theme to them, you could probably create "outer planes" that would feel more "normal" to players that have never "got" Planescape*.
* = I think Planescape is fine the way it is, but it does try to be "its own setting", rather than "the place people hang out when they die". If you had something that was more tied to the gods and the afterlife, characters would meet a number of NPCs from their own culture. They would also meet a number of NPCs from their culture's past. When you build an Arabian culture, you could also build the Arabian afterlife. A GM could even maybe run a Ghostwalk-style campaign if they accidentally have a TPK during an adventure and the PCs could go on a quest around the afterlife - an afterlife that works pretty much like a traditional fantasy world - in order to "win" the right to come back to the living world.
(If turned into an OGL version - with rules that work for 3.5 and Pathfinder - this could become a "Cosmological SRD".)
And as for Spelljammer**, as I said before, that can not
be used. But I think that a system that creates isolated "planetary systems" that can still connect with each other is a really cool idea. A sphere around a sun is a really logical thing, but that doesn't need to be the same sort of sphere that exists in spelljammer. One way to reboot the connectivity would be to have a "celestial sphere" that had stars on its surface and make each of those stars something like the Stargate in the TV series of the same name. Essentially every star on the surface of a "celestial sphere" could take people to a different "celestial sphere" surrounding a different solar system containing a different homebrew world a different commercial gameworld or even some content that a GM grabs from Dragonstar, Spelljammer, Space 1889 or anything else they want to use.
** = I also think that Spelljammer is fine the way it is, but I think that a fantasy space system that, by default, implied that every star in the sky was a portal to another planetary system, would be hundreds of times more epic in scope. I think the average player could instantly buy into the fact that spacefarers could (in one hop) go to thousands of different planetary systems. I think that the average player could instantly buy into the fact that nobody has managed to find out where the alien monsters that take the place of the beholders or illithids come from.
(If turned into an OGL version - again with rules that work for 3.5 and Pathfinder - this could become a "Fantasy Space SRD".)
Ironically, I think that a set of space rules that was spun off of my teleporting-star concept would probably fit better with what some of the Mystara fans want than the sphere-portal concept of Spelljammer. Because, if you drew a map of the stars and each star was a gateway to another planetary system, it would be possible to say that a type of creature or a race of humans had arrived from Epsion Eridani, because you would literally
fly a space-sailing-ship into the centre of Epsilon Eridani to get to where they come from. It would rob the game of "flow encounters", but would still retain all the other SJ control mechanisms (like isolating the gods within individual planetary systems).
The stuff I just said here was all made up on the spot, but if this stuff was actually thrashed out an entire system could be built that doesn't create different power levels between "spacefarers" and "groundlings" (or "planewalkers" and "clueless"). Interaction could actually be built into the system and made to be self regulating. "Groundlings" wouldn't go into space and hang about on asteroids near to the edge of the Celestial Sphere, because you would never know when an alien horde might come popping out of a random star. And "clueless" people wouldn't start planehopping, because when you got to the afterlife, you would sometimes be confronted by a bunch of NPCs that you had killed in earlier adventures (just imagine if they could somehow "steal" a PCs life and use that to get back to the real world).
I think that we could build a new cosmological system and/or a new interstellar system that would seem a bit more "normal" to people who haven't played with anything other than a traditional campaign world before and could be designed specifically with GM expansion in mind (because they say - right from the word go - there is no
end to this system).
As you said before, GMs could mix your world and other game worlds (specifically TSR worlds), but I think that we could go far beyond that and create an easy to use (yet still interesting to explore) system that allows a GM to use a Mystara adventure, a Dragonlance adventure, a Thorf's World adventure and then a RuneQuest adventure without actually rebooting those adventures to put them onto a planet they were never originally designed to be run on.
Even if you are not a major fan of Spelljammer or Planescape, you could downplay the flying through space thing and run a plot where the PCs are kidnapped by slavers and then taken to another planet via "the planes" or "star-teleportals" and then need to hop from planet to planet to planet looking for the way back home. It would be a really cool way to skim past SJ or PS concepts (with a bit of handwavium), but still get to crack out dozens of classic D&D campaign settings and other out of print stuff.
Thorf wrote:I guess the first goal would be to assemble an overview like the Mystara Newbie Guide - something like the "writers' bibles" many TV shows use to lay out the basic features of their setting. In our case nothing would be set in stone, though - and everyone would always be free to stray from the guide, and even create their own complete continuity of the world.
I'm sure that there are a ton of products out there that would serve as a good model to base a "writer's bible" on. And a lot of science fiction and fantasy TV shows have unofficial books that give an "A-Z of the <insert name of show>".