Worldbuilding is hard work, as we all know. When you want to write a story, or use a setting for a game, or just as inspiration for some creation (art, music), there is a strong incentive to reuse an existing world, or heavily derive from it. The world building has been done for you - the logic holes filled, the possibilities mapped and explored, the implications accounted for. I don't need to prove this, just look at all the fanfics out there.

However, if you do this with a well-known franchise, you infringe on intellectual rights, which limits how you can distribute or use your derived creation.

Similar to how open source and free culture licenses allow software and art to be reused and derived, are there any free (as in libre) world settings that are available for use? To limit the scope a bit, let's go for a typical, near-future science fiction setting: lasers, spaceships, aliens etc.

A good world setting would contain a bit more information than a standalone story; this is necessary for other authors/creators to extend and derive. It may contain the following:

  • Histories
  • Major factions and their motivations
  • Explanations of how fictional phenomena work (e.g. how fast is their FTL, where do their mages draw energy from)
  • The world revealed through multiple points of view, so we get a good cross-section

Do you know of such a piece of work? Please give a short description of what it is and how it's suitable, and not just a name-drop or link.

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    $\begingroup$ I'm divided about this question. I can see where it's coming from, but lists of references to external material, rather than specific answers to a specific question, is not something the Stack Exchange Q&A format is well suited for. For example, given a list of links and descriptions, what would be the criteria for voting? How do we know when (whether) the list is complete? And so on. Hence, I'm voting to close this as too broad primarily based on the number of potential answers. Consider How to deal with list questions?. $\endgroup$
    – user
    Commented Oct 10, 2014 at 12:35
  • $\begingroup$ @MichaelKjörling Isn't it a bit premature to close as too broad when there have been no direct answers yet? I have done some research on this and have not found any, hence asking here. Besides, we also have the software-recommendations tag which would also fit your criteria for too broad, and yet they are welcome. $\endgroup$ Commented Oct 10, 2014 at 13:27
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    $\begingroup$ Software recommendation questions are hard to get right. Broadness is not a property of the answers, rather it is a property of the question. Your comment doesn't appear to address the concerns raised in my comment (and corresponding close vote). If you'd like to discuss whether this type of question should be on topic, please don't do so in comments; make a post on Worldbuilding Meta and make your case there. $\endgroup$
    – user
    Commented Oct 10, 2014 at 13:40
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    $\begingroup$ I would word this question as: "Does this thing exist? If so, give me an example and an explanation of it to prove its existence." rather than asking for a list of them. Then accept the answer that provides the example that best suits what you were looking for. $\endgroup$ Commented Oct 10, 2014 at 17:26
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    $\begingroup$ Regardless of whether this question stays open, I've opened a meta discussion about the possibility of creating such a world through a series of questions on the site. $\endgroup$ Commented Oct 10, 2014 at 19:43

6 Answers 6


What you are talking about sounds like a shared universe.

There are a vast number of Shared Universes out there, with a wide range in licensing and IP restriction and ranging from amateur to professional. Some have detailed supporting and briefing information that anyone can pick up and use, others are restricted just to a small group of authors or people licensed or hired by a certain company.

For example the DC universe is controlled by DC comics and anything set in that universe needs their approval.

One example shared universe and a briefing on using it is Metamor Keep. (I don't actually know much about Metamor Keep, that link came up on a Google search for Shared Universes).

So depending on your exact requirements in terms of licensing and publishing rights, desired setting, style of writing, etc you should be able to search for an appropriate Shared Universe and use that. If you can't find one matching your needs then look into creating one!

  • $\begingroup$ Thanks, this gives me some background information, but most of the info in the Wikipedia article are about non-free universes - people must seek approval from owners first. There may be some older ones which have fallen into public domain but since they have been developed over the years, it's hard to figure out which parts are public domain and which are still under copyright (e.g. some of Sherlock Holmes's stories are still protected). Metamor Keep looks like a medieval/fantasy setting, plus the licensing is unclear to me - it appears it's not free, you must seek approval from the community. $\endgroup$ Commented Oct 10, 2014 at 9:38
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    $\begingroup$ @congusbongus Yeah, unfortunately I'm not aware of any that match your exact requirements so all I can do is give you the background information and suggest where to start looking. $\endgroup$
    – Tim B
    Commented Oct 10, 2014 at 9:47

I haven't had a chance to look much into it, but there is Orion's Arm, which is a shared universe that has become well-established, and is a sort of post-singularity, trans-humanist, space-opera.

According to the summary on Wikipedia:

Orion's Arm, (also called the Orion's Arm Universe Project, OAUP, or simply OA) is a multi-authored online science fiction world-building project, first established in 2000 by M. Alan Kazlev, Donna Malcolm Hirsekorn, Bernd Helfert and Anders Sandberg and further co-authored by many people since. It was described by Cory Doctorow as "a pretty thoroughgoing post-Singularity thinggum with lots of opportunity for fun noodling". Anyone can contribute articles, stories, artwork, or music to the website. A large mailing list exists, in which members debate aspects of the world they are creating, discussing additions, modifications, issues arising, and work to be done.

  • $\begingroup$ Very interesting; unfortunately it doesn't quite fit the bill as it's set "over ten thousand years in the future". $\endgroup$ Commented Oct 10, 2014 at 23:46
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    $\begingroup$ Ah, sorry, I completely missed the "near-future" requirement. Although I get the impression they might have stories set throughout that entire stretch of history, so its possible there are some that are nearer future than others. $\endgroup$ Commented Oct 11, 2014 at 0:07
  • $\begingroup$ @CalebHines, you're absolutely right on that point. Have a look at the timeline of important events. It starts with 0 a.t., which is the date of the moon landing (in a new calendar), and extends continuously into the future, some 10 millenia far. The earliest periods (the centuries after the moonlanding) are studded with events. $\endgroup$
    – Turion
    Commented Mar 7, 2017 at 13:47
  • $\begingroup$ @congusbongus I wish to note what was said about the OA universe having a history so it would be possible to set events early in the OA history. $\endgroup$
    – P Chapman
    Commented Dec 20, 2017 at 20:35

The Paradisi Chronicles

The Paradisi Chronicles are set in 100-300 years in the future, when a group of people decide to colonize a new planet in the Paradisi system and leave the collapsing earth behind:

By 2092 AD, the Paradisi Project has achieved its goals. With Earth continuing on its path to destruction, a fleet of ten ships are launched, each carrying 10,000 passengers––Founding Family members, their loyal employees, and the staff necessary to build a new civilization once their journey ends.


They meet humanoid aliens with psychic powers, have intrigues and rebellions, and finally get contacted by some of the people who remained on earth longer.

A major downside: Lack of openness

The Paradisi Universe blows its own trumpet by calling itself "An open-source scifi universe". But it's not all as accessible as you might think:

  • Nowhere on the website can I find detailed licensing informations.
  • Paradisi is focussed on writing books mainly, it seems. That's absolutely ok in itself. But the books are of course not under an open license and you need to buy them. (There are a few free ebooks, though. ("Free" as in "free beer", not as in "free speech".)
  • There is a "World Bible", which contains out lots of details about the fictional universe, but you can't access it online. You need to send someone an email (see here) and they'll send you a copy. No idea why this model was chosen over a read-only wiki. I asked for a copy and got a wary answer asking for my plans with the World Bible, and after responding to it I didn't receive a further answer at all.
  • In some books, there are links to password protected parts of the website with new, hidden material.

So in conclusion, I must say that the Paradisi Chronicles are not an open universe, despite self-proclaiming to be so.

The Fifth World

Not so much aliens and spaceships, but a seemingly very solid postapocalyptic world set on earth in ca. 400 years from now.

The Fifth World presents an open source shared universe — a vision of a neotribal, ecotopian, animist realist future created by a growing community of authors, artists, designers, gamers, and dreamers — and we want you to join us.

The Fifth World is centered around a pen-and-paper RPG that you can download for free.


The Fifth World takes openness seriously.

  • The content is all under Creative Commons Share Alike.
  • There is a great wiki with all of the content of the world, viewed from the outside perspective (etic) and the inside perspective (emic). Everyone who shows sufficient motivation can become a contributor to the wiki.
  • There is a free novel set in The Fifth World that you can read.

A minor downside: Work in progress

While this might also apply to Paradisi (although they don't talk about that), The Fifth World is still work in progress, and gladly they are very frank about that. The game is in beta-testing, it seems, and the novel is one third finished. But, hey, that means there is a lot of space for you to fill!


The SCP Foundation is a shared science fiction world with what seems to me an Xfiles sort of vibe. It operates under a Creative Commons license. http://www.scp-wiki.net/licensing-guide

Their website is a repository for works of fiction. I was surprised how uniformly good the writing was. You can easily lose a couple of hours poking around.

The mission statement for the fictional Foundation:


Mission Statement

Operating clandestine and worldwide, the Foundation operates beyond jurisdiction, empowered and entrusted by every major national government with the task of containing anomalous objects, entities, and phenomena. These anomalies pose a significant threat to global security by threatening either physical or psychological harm.

The Foundation operates to maintain normalcy, so that the worldwide civilian population can live and go on with their daily lives without fear, mistrust, or doubt in their personal beliefs, and to maintain human independence from extraterrestrial, extradimensional, and other extranormal influence.

Our mission is three-fold:

The Foundation secures anomalies with the goal of preventing them from falling into the hands of civilian or rival agencies, through extensive observation and surveillance and by acting to intercept such anomalies at the earliest opportunity.

The Foundation contains anomalies with the goal of preventing their influence or effects from spreading, by either relocating, concealing, or dismantling such anomalies or by suppressing or preventing public dissemination of knowledge thereof.

The Foundation protects humanity from the effects of such anomalies as well as the anomalies themselves until such time that they are either fully understood or new theories of science can be devised based on their properties and behavior. The Foundation may also neutralize or destroy anomalies as an option of last resort, if they are determined to be too dangerous to be contained.

  • $\begingroup$ Reminds me of an old role playing game by Tri-Tac called "Stalking the Night Fantastic". Sort of the love child of Men-in-Black and X-Files, but pre-dating both of them. I will definitely be looking into this. Thanks! $\endgroup$ Commented Mar 8, 2017 at 5:34
  • $\begingroup$ I got the feeling that SCP was a theme, not a shared world. Vignettes about artifacts don’t need common characters etc. $\endgroup$
    – JDługosz
    Commented Mar 8, 2017 at 7:18
  • $\begingroup$ The SCPs would be the characters. Individual SCPs feature in stories about other SCPs. I have also seen mention of specific events and researchers referenced in more than one vignette (exactly what they are). It must take vigilance to make sure things stay internally consistent. $\endgroup$
    – Willk
    Commented Mar 9, 2017 at 0:05

Hal Clement's planet Mesklin

This first appeared in his novel Mission of Gravity (1953). Mesklin is a gold standard hard science planetary setting.

Mesklin is a fictional supergiant planet created by Hal Clement and used in a number of his hard science fiction stories.

It is distinctive for the interaction of its strong gravity with the centrifugal force due to its fast rotation, originating, according to Clement's original calculations, a gee force gradient, starting at 3 g on the equator, and ending at 665 g on the planet's poles.

Further details can be explicated below.

Clement described the basic characteristics of Mesklin in the article "Whirligig World" in Astounding Science Fiction (June 1953). He based the world on an object then thought to exist in the 61 Cygni system, which had been detected by analysis of the motion of the two already known stars in the system. Further analysis with more extensive data led to the conclusion that the find had been erroneous.

Clement decided, since its mass was 16 times that of Jupiter, Mesklin would have an extremely large angular frequency to partly counter its gravity in order to allow humans to visit part of it. He wanted the equatorial gravity to be 3 g, so he determined the period necessary to make this occur: each Mesklin day is 17.75 minutes long given that the planet rotates approximately 20 degrees a minute.

As a result of this extremely large rate of spin, Mesklin is not even slightly spherical; it has a large equatorial bulge. Mesklin's equatorial diameter is 48,000 miles (77,250 km), while from pole-to-pole along its axis of rotation it is 19,740 miles (31,770 km). Then Clement attempted to calculate the polar gravity, finding it surprisingly difficult. He admits, "To be perfectly frank, I don't know the exact value of the polar gravity; the planet is so oblate that the usual rule of spheres... would not even be a good approximation..." "Whirligig World" reports his initial calculations of the pole gravity to be 655 g; the dust jacket of Heavy Planet reports it as 700 g. A later program created by Clement computed it as 275 g, as did a similar program written by the MIT Science Fiction Society. The MIT group also concluded that the planet would have had a sharp edge at the equator.1 Clement also gave Mesklin a set of rings and massive moons. The inner moon is 90,000 miles (140,000 km) from the planet's center, with a period of 2 hours 8 minutes.[2]

Clement assumed Mesklin's orbit around its star (which he decided would be 61 Cygni A) took 1,800 Earth-days, and was highly elliptical: at its closest point the average temperature would be −50 °C, while at the furthest its average temperature would be −180 °C. Since the orbit is eccentric it moves rapidly past its sun at the closest point, so its temperature would be around −170 °C most of the time.

Clement decided this imaginary world would have native life-forms, that they would be based on methane (CH4), and there would be oceans of methane. However, methane has a low boiling point, suggesting that Mesklin's sun might boil its oceans and cause the methane to escape the planet entirely. Thus, the writer arranged the planet so its northern hemisphere's midsummer occurs when it is nearest its sun. Thus, the northern hemisphere would develop a large frozen methane cap during most of its year; the southern hemisphere (where most creatures live) is protected from the sun's closest approach by the rest of the planet. He also asserted the planet would have a fairly rapid precession.

Considering Clement published his novel about Mesklin in 1953, yet it sounds like one of the exoplanets discovered in the last couple of decades.

Importantly, Clement made the following magnanimous offer to open this planetary setting to other authors.

In "Whirligig World", Clement stated he gave "official permission to anyone who so desires to lay scenes there [in Mesklin]. I ask only that he maintain reasonable scientific standards, and that's certainly an elastic requirement in the field of science fiction."

Effectively this offer for other authors to use Mesklin has been available since 1953. To date no-one has taken it up. As a courtesy, any author writing stories set on Mesklin should contact the Clement estate before doing so. Hal Clement (real name Harry Stubbs) died in 2001. Please note the only restriction is maintaining reasonable scientific standards, and even there Clement was indicating that some measure of flexibility is allowed.

Clement has done all the hard work of building the planet. While various studies have expanded and extended on the characteristics of Mesklin. More recently the Australian physicist Ditmar Jenssen analyzed Mesklin in detail. Tjis was published in the fanzine Interstellar Ramjet Scoop circa 2004.

This isn't a shared world, they came much later, circa the 1980s or 1990s, and it isn't open source fiction where creative commons licenses are expected. It is, surprise, surprise, a science-fiction setting that is open to any science-fiction author who wants to write a story there.

Source: Mesklin


A point of clarification about the intellectual property rights inherent in Clemen's Mesklin. Although Clement publicly granted access to his created imaginary planet, the ownership of the IP rights presumably now reside with his estate, therefore, it will be necessary to contact his heirs and successors.

They may have the power the rescind this open access, and it is for this reason any writer intending to use Mesklin as a setting they should first contact his estate both as a courtesy and ensure it is permissible to do so.

However, a good case could be put to his surviving family that having other authors write about Mesklin was well within Hal Clement's own explicitly stated wishes, even as long ago as 1953, and to do so would be a fitting tribute to his memory and a celebration of his work.

As the question said: "The world building has been done for you - the logic holes filled, the possibilities mapped and explored, the implications accounted for." Mesklin has been open for business by other writers since 1953. Hal Clement was scrupulous worldbuilder. He had given a clear indication that other writers were allowed to play there and in a manner that should permit an open legal license to do so. The pity is no-one had taken him up on the offer.

  1. Larry Niven Man-kzin wars portion of the known space universe is open to use, 300 years of the 1000 his stories are set in, several aliens species to work with, each with so rather creative biology and quirks.

    FTL is hyperspace type travel (that requires a living mind to steer), there are ways to introduce weird one shot things (Slaver artifacts, basically leftovers from a war that ended almost all intelligent life in the galaxy but).

    Psychic powers are real but very weak, the strongest telekinetic in existence can just lift a cigarette, telepaths are a bit stronger but rarely sane.

    Humans come is several flavors because the probes sent to find habitable planets had a bit too loose of a definition of habitable, so you heavy worlders, mooner, albino crashlanders, ect.

    You can read more here https://en.wikipedia.org/wiki/Known_Space

  2. The Orion's Arm setting is a collective universe project, http://www.orionsarm.com/ It is a collective very hard science setting. It is basically designed to be a communal setting for stories.

    • Matter cannot travel faster than light
    • Matter and energy are conserved
    • No evolved humanoid aliens have been discovered
    • Technology will change the nature of social issues
    • A logical explanation for even the most fantastic elements within the setting must be provided.
    • Space is vast expect the same challenges to have many different solutions, or as we say at Orion's Arm - Diversity! Diversity! Diversity!
  • $\begingroup$ I do not think that this answer actually satisfies the asker's question. They are looking for a setting that is open source and Known Space looks to be Larry Niven's and Larry Niven's only. $\endgroup$ Commented Dec 21, 2017 at 3:51
  • $\begingroup$ As I said the man kzin war period has been open to and used by other authors for decades. $\endgroup$
    – John
    Commented Dec 21, 2017 at 11:20
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    $\begingroup$ I think you will find the Man-Kzin Wars are available under license to other authors. They aren't available to all-comers. The Man-Kzin Wars anthologies and novels are effectively a shared world and like most shared worlds permission is needed to become a contender. $\endgroup$
    – a4android
    Commented Dec 21, 2017 at 11:34
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    $\begingroup$ More information can be found here: en.wikipedia.org/wiki/Man-Kzin_Wars The origins of MKW ouevre was "there was a large fan demand for stories covering the conflict, and a number of his author friends had shown interest in writing tales set in the timeframe. Niven therefore allowed the Man-Kzin Wars to become a shared universe, starting with the 1988 release of The Man-Kzin Wars." $\endgroup$
    – a4android
    Commented Dec 21, 2017 at 11:38

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