Difference between revisions of "Open Game Systems"

From RPGnet
Jump to: navigation, search
(rv vandalism, several layers worth)
('Copyright Free')
(42 intermediate revisions by 23 users not shown)
Line 1: Line 1:
[[Category:OpenLicense]]
+
This page collects games released under an open license. Generally speaking, if something is available under an open license it is free for use and re-use as long as the terms of its license are respected, without any explicit contact or negotiation between original author and licensee. Requirements vary from offering no restriction whatsoever to requiring that you credit the authors or that you also allow others to use your own derivative work freely.
  
> A more up-to-date list of open games can be found on the [http://livingfree.wikidot.com/list-of-libre-games Year of Living Free wiki].
+
The most common use of these licenses is for the original authors to inform other people interested in using their system that they are legally able to do so and even sell their own new work without having to pay anything to the original authors - however, even if those are intended as a gesture of good will and openness, failing to respect all of the terms from a license may leave you exposed to a lawsuit from the original creators.
  
This page collects all the games under an open license like the [[Open Game License]] and various [http://en.wikipedia.org/wiki/Creative_Commons_licenses Creative Commons Licenses].  
+
Using an openly-licensed system for your own products (books, video games, card games...) means that you are able to rely on the work of others instead of having to design, write, playtest and balance your own. It also allows a product to become part of a larger community - which may draw those players (since they're already familiar with the rules) or allow them to combine your product with others that use the same system.
  
= Definition: What is an Open License? =
+
Here is a brief description of each major license found on the list below. Note, however, that details vary from license to license - so if you're planning on doing anything more than using the systems below for personal play, you should get acquainted with the full text of the license:
  
This page operates under the following definition:
+
* '''[[Open Game License]] (OGL)''': the OGL allows for differentiation between ''Open Game Content'' (parts of the system that others can use freely) and ''Product Identity'' (parts that are not open for others to use). Some publishers also create a [https://en.wikipedia.org/wiki/System_Reference_Document System Reference Document (SRD)], which is a version of the system containing only the Open Game Content, without any Product Identity.
 +
* '''Creative commons (CC)''': a family of permissive licenses that usually require only that you credit the original authors when using their work. Authors are free to choose from any of the CC licenses available - to read more about the differences between each, visit their [https://creativecommons.org/licenses/ official website].
 +
* '''GNU licenses (GPL and GFDL):''' designed for distribution of computer code and programs, this license allows you to use original work freely. However, if you are creating a modification of said work (for example, a set of alternative rules), you are required to make your own work available through the GPL license as well. If you are not modifying the original work, but only using it to create something entirely new (for example, a book with new characters and monsters to use) then you are not required to distribute it under the GPL. There are many versions of this license available, the most popular arguably being the GPLv2 - for more information about each version and related licenses see [https://www.gnu.org/licenses/licenses.en.html the official GNU website].
  
"An Open License allows the free and perpetual re-use of original material by anybody willing to follow the restrictions of said license, without an explicit contact or negotiation between original author and licensee."
+
Some open games, despite being free to use and modify in derived work, require you to buy a printed book or PDF copy to learn the rules. The list below should only contain examples of systems that are also 100% free to acquire digitally - or at least allow you to look up most of the rules online.
  
In other words, if something is available under an open license, I can use and re-use it for free, as long as I respect the restrictions laid out in the license, without having to contact the author.
+
== Open Game License ==
 +
* [http://www.wizards.com/d20/files/OGLv1.0a.rtf Original OGL]
 +
* [[Dungeons and Dragons]] 3.5 [http://www.wizards.com/default.asp?x=d20/article/srd35 SRD]
 +
* [http://www.d20srd.org/index.htm Hypertext D&D 3.5 SRD]
 +
* [http://d20pfsrd.com/  Pathfinder SRD]
 +
* [http://www.wizards.com/default.asp?x=d20/article/msrd d20 Modern SRD]
 +
* [[Dungeons and Dragons]] 5 [http://media.wizards.com/2016/downloads/DND/SRD-OGL_V5.1.pdf SRD]
  
= Retroclones =
+
Note that the official d20 SRD for D&D 3e has been revoked. It has been replaced by Paizo's Pathfinder SRD, which is compatible with previous d20 material and still being used for publication of new products by many companies and the community at large.
  
'''Retro-clones''' are new games that are compatible with games that are now out-of-print. They are listed separately to the other games.
+
=== d20 System-based  ===
 +
* [http://www.faterpg.com/dl/animed20srd.pdf d20 Anime SRD] (direct link to file)
 +
* [http://yeoldegamingcompanye.com/wayfarersmain.htm Wayfarers] (OGL and open-ended agreement)
 +
* [http://www.prometheusgaming.com/ Prometheus SRD] (OGL and Prometheus License)
 +
* [http://www.mutantsandmasterminds.com/ Mutants & Masterminds] (OGL and [http://www.mutantsandmasterminds.com/superlink/000080.php M&M Superlink])
 +
* [http://true20.com/ True20] (OGL and [http://true20.com/licensing/True20TrademarkLicense.htm True20 Adventure Roleplaying Trademark License])
  
= The List: =
+
=== d6 based ===
 
+
* [http://opend6project.org/ OpenD6] SRD-like page [http://opend6.wikia.com/OpenD6 Wikia collection page]
The following systems are available under an open license and are thus free to use in your own publications. (Though with varying restriction on the use of the material.)
+
* [http://opend6.wikia.com/Cinema_6 Cinema 6]
 +
=== Fudge-based ===
 +
* [http://www.faterpg.com/dl/Fate-SRD-2005-03-31.rtf Fate 2.0] (direct link to the file)
 +
* [http://www.faterpg.com/dl/sotc-srd.html Spirit of the Century]
 +
* [http://www.vsca.ca/Diaspora/diaspora-srd.html Diaspora]
  
 +
=== Other systems ===
 +
* [http://rpg.drivethrustuff.com/product_info.php?products_id=29076 Iridium System]
 +
* [http://www.darkshire.net/jhkim/rpg/srd/srd_runic/index.html Runic], Runequest RPG
 +
* [http://www.drivethrurpg.com/product/68843/Spellchrome-Core-Rulebook/ Spellchrome] (OGL and Non-Open Game Content)
 +
* [http://www.crafty-games.com/ Fantasy Craft] (OGL)
  
== D&D [[Open Game License]] ==
+
=== [https://en.wikipedia.org/wiki/Dungeons_%26_Dragons_retro-clones Retro-Clones] ===
([http://www.wizards.com/d20/files/OGLv1.0a.rtf Direct Link])
+
'''Retro-clones''' are new games that are compatible with older games now out-of-print, allowing for the use of previous material without having to acquire a possibly rare and/or expensive copy of the original game or resorting to piracy. These are part of a larger movement known as the [https://en.wikipedia.org/wiki/Old_School_Revival Old-School Renaissance (OSR)].
* [http://www.wizards.com/default.asp?x=d20/article/srd35 d20 System 3.5 SRD], [[Dungeons and Dragons]] (OGL and [[d20 System License]] - revoked)
 
* [http://www.wizards.com/default.asp?x=d20/article/msrd Modern d20 SRD]
 
  
=== Retro-Clones ===
 
 
* [[OSRIC]] for 1E AD&D ([http://www.knights-n-knaves.com/osric download]) (OGL and OSRIC Open License)
 
* [[OSRIC]] for 1E AD&D ([http://www.knights-n-knaves.com/osric download]) (OGL and OSRIC Open License)
 
* [[Labyrinth Lord]] for B/X D&D ([http://www.goblinoidgames.com/labyrinthlord.html download] or [http://grandwiki.wikidot.com/ll view wiki]) (OGL and [http://www.goblinoidgames.com/ll_license1.zip Labyrinth Lord Trademark License])
 
* [[Labyrinth Lord]] for B/X D&D ([http://www.goblinoidgames.com/labyrinthlord.html download] or [http://grandwiki.wikidot.com/ll view wiki]) (OGL and [http://www.goblinoidgames.com/ll_license1.zip Labyrinth Lord Trademark License])
Line 35: Line 54:
 
* [[Warrior & Wizard]] for [[The Fantasy Trip]] (download [http://docs.google.com/Doc?docid=dcsfz7gv_9gzdh7hdz&hl=en CC] or [http://docs.google.com/View?id=dcsfz7gv_22xmrn2sgg OGL] version or [http://4csystem.wikidot.com/w-w-srd view wiki]) (Creative Commons Attribution-ShareAlike and OGL; Direct link to file)
 
* [[Warrior & Wizard]] for [[The Fantasy Trip]] (download [http://docs.google.com/Doc?docid=dcsfz7gv_9gzdh7hdz&hl=en CC] or [http://docs.google.com/View?id=dcsfz7gv_22xmrn2sgg OGL] version or [http://4csystem.wikidot.com/w-w-srd view wiki]) (Creative Commons Attribution-ShareAlike and OGL; Direct link to file)
  
=== d20 System Based OGL ===
+
=== OGL with trademark license ===
* [http://www.faterpg.com/dl/animed20srd.pdf d20 Anime SRD] (direct link to file)
 
* [http://yeoldegamingcompanye.com/wayfarersmain.htm Wayfarers] (OGL and open-ended agreement)
 
* [http://www.prometheusgaming.com/ Prometheus SRD] (OGL and Prometheus License)
 
* [http://www.mutantsandmasterminds.com/ Mutants & Masterminds] (OGL and [http://www.mutantsandmasterminds.com/superlink/000080.php M&M Superlink])
 
* [http://true20.com/ True20] (OGL and [http://true20.com/licensing/True20TrademarkLicense.htm True20 Adventure Roleplaying Trademark License])
 
 
 
== Other Systems Using OGL ==
 
* [http://rpg.drivethrustuff.com/product_info.php?products_id=29076 Iridium System]
 
* [http://www.battlefieldpress.com/?q=node/17 Open Core Roleplaying System] - uses Open Content from several OGL systems
 
* [http://www.darkshire.net/jhkim/rpg/srd/srd_runic/index.html Runic], Runequest RPG
 
* [http://www.spellchrome.com/ Spellchrome] (OGL and Non-Open Game Content)
 
 
 
== Open Game License and Trademark License ==
 
  
These games release their material as Open Game Content, but also provide another, more restricted, license to allow publishers to refer to Product Identity.
+
These games release their material as Open Game Content but also provide another, more restricted license to allow publishers to refer to Product Identity.
  
 
* [http://www.goblinoidgames.com/mutantfuture.htm Mutant Future] (OGL and Mutant Future Trademark License)
 
* [http://www.goblinoidgames.com/mutantfuture.htm Mutant Future] (OGL and Mutant Future Trademark License)
Line 57: Line 63:
 
* [http://www.roninarts.com/store/default.php?cPath=5_14 vsM Engine]
 
* [http://www.roninarts.com/store/default.php?cPath=5_14 vsM Engine]
  
===Fudge based===
+
== Creative Commons licenses ==
* [http://www.faterpg.com/dl/Fate-SRD-2005-03-31.rtf Fate 2.0] (direct link to the file)
+
 
* [http://www.faterpg.com/dl/sotc-srd.html Spirit of the Century]
+
=== Creative Commons Attribution ===
* [http://www.vsca.ca/Diaspora/diaspora-srd.html Diaspora]
+
* [https://web.archive.org/web/20071026121622/http://tsoy.crngames.com/ The Shadow of Yesterday] (Attribution)
 +
* [http://www.lulu.com/content/866835 Wushu Open] (Attribution)
 +
** Parts are available [https://web.archive.org/web/20130507114737/http://danielbayn.com/wushu/WushuOpen.rtf here] (direct link) but the file is 10 pages while the book was 40 pages.
 +
** Same content is available on [https://web.archive.org/web/20120218063632/http://wiki.saberpunk.net/Wushu/WushuOpenRules this] website.
 +
* [https://mozai.com/writing/not_mine/shadows.html Shadows] (Attribution)
 +
* [https://allenkerensky.com/_media/adventurer_guide.pdf Myriad] (Attribution)
 +
* [https://www.vajraenterprises.com/new/?p=132 Organic Rules Components (ORC)] (Attribution)
 +
* [https://tinyd10.com/ Tiny d10] (Attribution 4.0)
 +
* [http://brentnewhall.com/games/gunwave/Gunwave_PDFs_Complete.zip Gunwave] (Attribution 3.0)
  
== Creative Commons Licenses ==
+
=== Creative Commons Attribution Share Alike ===
 
* [http://6d6rpg.com/ 6d6 RPG] 6d6 Fireball (Attribution-Share Alike)
 
* [http://6d6rpg.com/ 6d6 RPG] 6d6 Fireball (Attribution-Share Alike)
 +
* [http://open.crngames.com/src/donjon.html Donjon] (Attribution/Share-Alike)
 +
* [http://wiki.saberpunk.net/Wushu/OpenReloaded Wushu Open Reloaded] (Attribution/Share-Alike)
 +
* [http://tower.newcenturycomputers.net/tsgs.html The Simple Game System (TSGS)] (Attribution/Share-Alike)
 +
 +
=== Creative Commons Attribution Non-Comercial ===
 +
* [http://www.allenvarney.com/noteworthy.html Noteworthy] (Attribution/Non-Commercial)
 +
* [http://www.scribd.com/doc/16493874/Sufficiently-Advanced Sufficiently Advanced] (Attribution/Non-Commercial)
 +
 +
=== Creative Commons Attribution Non-Comercial Share Alike ===
 
* [http://www.eclipsephase.com/ Eclipse Phase] Posthuman Studios (Attribution-Noncommercial-Share Alike 3.0 Unported License)
 
* [http://www.eclipsephase.com/ Eclipse Phase] Posthuman Studios (Attribution-Noncommercial-Share Alike 3.0 Unported License)
 
* [http://www.bullypulpitgames.com/games/index.php?game=drowning_and_falling Drowning and Falling] (Attribution/Non-Commercial/Share-Alike)
 
* [http://www.bullypulpitgames.com/games/index.php?game=drowning_and_falling Drowning and Falling] (Attribution/Non-Commercial/Share-Alike)
* [http://tsoy.crngames.com/ The Shadow of Yesterday] (Attribution)
 
* [http://open.crngames.com/src/donjon.html Donjon] (Attribution/Share-Alike)
 
* [http://www.lulu.com/content/866835 Wushu Open] (Attribution)
 
* [http://wiki.saberpunk.net/Wushu/OpenReloaded Wushu Open Reloaded] (Attribution/Share-Alike)
 
* [http://www.harlekin-maus.com/games/shadows/shadows.html Shadows] (Attribution)
 
* [http://www.sanestudios.co.uk Myriad] (Attribution)
 
* [http://www.fatesworsethandeath.com/ORC/index.htm Organic Rules Components (ORC)] (Attribution)
 
 
* [http://www.costik.com/weblog/2005_08_01_blogchive.html#112454587656432430 Violence] (Attribution/Non-Commercial/Share-Alike)
 
* [http://www.costik.com/weblog/2005_08_01_blogchive.html#112454587656432430 Violence] (Attribution/Non-Commercial/Share-Alike)
 
* [http://rpg.starwreck.com Star Wreck] (Attribution/Non-Commercial/Share-Alike)
 
* [http://rpg.starwreck.com Star Wreck] (Attribution/Non-Commercial/Share-Alike)
* [http://www.allenvarney.com/noteworthy.html Noteworthy] (Attribution/Non-Commercial)
 
 
* [http://gregstolze.com/ExecutiveDecision.zip Executive Decision] (Attribution/Non-Commercial/Share-Alike; direct link to file)
 
* [http://gregstolze.com/ExecutiveDecision.zip Executive Decision] (Attribution/Non-Commercial/Share-Alike; direct link to file)
 
* [http://gregstolze.com/inSpaaace.zip ...in Spaaace!] (Attribution/Non-Commercial/Share-Alike; direct link to file)
 
* [http://gregstolze.com/inSpaaace.zip ...in Spaaace!] (Attribution/Non-Commercial/Share-Alike; direct link to file)
* [http://www.scribd.com/doc/16493874/Sufficiently-Advanced Sufficiently Advanced] (Attribution/Non-Commercial)
 
 
* [http://www.treasurerpg.com/ Treasure] (Attribution/Non-Commercial/Share-Alike)
 
* [http://www.treasurerpg.com/ Treasure] (Attribution/Non-Commercial/Share-Alike)
* [http://tower.newcenturycomputers.net/tsgs.html The Simple Game System (TSGS)] (Attribution/SHare-Alike)
 
 
* [http://www.dangerpatrol.com/ Danger Patrol] (Attribution/Non-Commercial/Share-Alike)
 
* [http://www.dangerpatrol.com/ Danger Patrol] (Attribution/Non-Commercial/Share-Alike)
 
* [http://www.onesevendesign.com/ladyblackbird/ Lady Blackbird] (Attribution Non-Commercial Share-Alike)
 
* [http://www.onesevendesign.com/ladyblackbird/ Lady Blackbird] (Attribution Non-Commercial Share-Alike)
 
* [http://www.emptygamebox.com/iliamna-unknown Iliamna Unknown] (Attribution Non-Commercial Share-Alike)
 
* [http://www.emptygamebox.com/iliamna-unknown Iliamna Unknown] (Attribution Non-Commercial Share-Alike)
* [http://yggdrasildistro.wordpress.com/free-diy-roleplaying-material-including-rugs-and-saga/ Saga, a rules-light narrative universal system] (Attribution/Non-Commercial/Share-Alike)
+
* [http://yggdrasildistro.wordpress.com/free-diy-roleplaying-material/ Saga, a rules-light narrative universal system] (Attribution/Non-Commercial/Share-Alike)
 
* [http://www.jumpersrpg.com/ Jumpers, a multi-dimensional, multi-genre sci-fi RPG] (Attribution-Noncommercial-Share Alike 3.0 Unported License)
 
* [http://www.jumpersrpg.com/ Jumpers, a multi-dimensional, multi-genre sci-fi RPG] (Attribution-Noncommercial-Share Alike 3.0 Unported License)
  
 
== GNU licenses ==
 
== GNU licenses ==
 +
 
* [http://www.godsmonsters.com/ Gods and Monsters] (GNU Free Documentation License)
 
* [http://www.godsmonsters.com/ Gods and Monsters] (GNU Free Documentation License)
 
* [http://worldforge.org/dev/content/rules/circe/ Circe] (GNU Free Documentation Licence and GNU General Public License)
 
* [http://worldforge.org/dev/content/rules/circe/ Circe] (GNU Free Documentation Licence and GNU General Public License)
 
* [http://webdav.freeroleplay.org/fringe/trunk/ Fringe] (OpenOffice Writer format) (GNU General Public License)
 
* [http://webdav.freeroleplay.org/fringe/trunk/ Fringe] (OpenOffice Writer format) (GNU General Public License)
  
== Other ==
+
== 'Copyright Free' ==
 +
''These works are generally free to be used commercially, without attribution, and without requiring derivative works be shared under the same licence (copyleft). Works are typically placed here because: 1. their copyright term has ended; <!-- please note if this is in the country of publication or just a group of other countries -->2. their author placed them into the public domain; or 3. their author gave them a licence that allows them to be used effectively as public domain.''
 +
* [[Redbox Hack]] ([http://4csystem.wikidot.com/redbox-hack-2-srd view wiki]) (license unclear; readers told to "do what you'd like with the thing").
 +
** [http://www.oldschoolhack.net/osh-docs/RBH2.pdf PDF]
 +
* [[4C System]] for the Marvel RPG ([http://hazardstudio.net/sitebuildercontent/sitebuilderfiles/4csystem.zip download]) (Public Domain; Direct link to file)
 +
* [https://sites.google.com/a/amagi-games.net/amagi-games/games-archive The Amagi Games Archive] (Public Domain) - a number of games by Levi Kornelsen including
 +
** The Far Towers
 +
** Microcosm
 +
* [https://archive.org/details/Hoard-RPG Hoard] (Public Domain) another of Kornelsen's games
 +
* Several games by Gurbintroll Games:
 +
** [https://gurbintrollgames.wordpress.com/blood-guts-glory/ Blood, Guts and Glory] (public domain except for some terms using the OGL - retroclone)
 +
** [https://gurbintrollgames.wordpress.com/dark-dungeons/ Dark Dungeons and Dark Dungeons X] (public domain except for some terms using the OGL - retroclone of the 'Rules Cyclopedia' 1991 edition of 'basic' Dungeons and Dragons)
 +
** [https://gurbintrollgames.wordpress.com/codename-spandex/ Codename: Spandex] (all text is public domain - retroclone)
 +
** [https://gurbintrollgames.wordpress.com/immortals-companion/ Immortals Companion] (public domain except for some terms using the OGL - update of the Immortals Set for D&D 5e)
 +
* H.G. Well's early 'roleplaying game like' [https://www.gutenberg.org/ebooks/3690 Floor Games] and [https://www.gutenberg.org/ebooks/3691 Little Wars] (published in the UK where they are public domain)
 +
* [https://archive.org/details/enchanted-realms Enchanted Realms] "free for anyone to take an use as they wish"
 +
* [https://archive.org/details/super-hero-fun Super Hero Fun] "no rights reserved"
 +
 
 +
== Other licenses ==
 +
 
 
* [http://www.dominionrules.org/ Dominion Rules] (Dominion Rules Licence)
 
* [http://www.dominionrules.org/ Dominion Rules] (Dominion Rules Licence)
 
* [http://rpg.drivethrustuff.com/product_info.php?products_id=28830 Action! System] (Action! System Open License)
 
* [http://rpg.drivethrustuff.com/product_info.php?products_id=28830 Action! System] (Action! System Open License)
 
* [http://rpg.drivethrustuff.com/product_info.php?products_id=2589 Active Exploits] (Active Exploits Distribution and Expansion License)
 
* [http://rpg.drivethrustuff.com/product_info.php?products_id=2589 Active Exploits] (Active Exploits Distribution and Expansion License)
* [[Redbox Hack]] ([http://4csystem.wikidot.com/redbox-hack-2-srd view wiki]) (license unclear; readers told to "do what you'd like with the thing").
 
 
* [[Dungeons and Dragons Fourth Edition]] ([http://www.wizards.com/default.asp?x=d20/welcome Game System License])
 
* [[Dungeons and Dragons Fourth Edition]] ([http://www.wizards.com/default.asp?x=d20/welcome Game System License])
 
* [http://basicroleplaying.com/forum/downloads.php?do=file&id=11 Fire and Sword] 4E (Free Art License)
 
* [http://basicroleplaying.com/forum/downloads.php?do=file&id=11 Fire and Sword] 4E (Free Art License)
* [[4C System]] for the Marvel RPG ([http://hazardstudio.net/sitebuildercontent/sitebuilderfiles/4csystem.zip download]) (Public Domain; Direct link to file)
 
* [http://www.amagi-games.org/danger-rolls The Far Towers] (Public Domain)
 
* [http://www.amagi-games.org/token-wagering Hoard 1st Edition and Microcosm] (Public Domain)
 
 
* [http://www.theonosis.com Theonosis, an open fantasy setting] - The [http://www.osl.theonosis.com Open Setting License] allows the setting to be used with any game.
 
* [http://www.theonosis.com Theonosis, an open fantasy setting] - The [http://www.osl.theonosis.com Open Setting License] allows the setting to be used with any game.
 +
 +
== External links ==
 +
 +
* List of open tabletop games at the [http://fossilbank.wikidot.com/category:tabletop-game-libre FOSsil Bank wiki].
 +
 +
[[Category:OpenLicense]]

Revision as of 06:09, 20 February 2021

This page collects games released under an open license. Generally speaking, if something is available under an open license it is free for use and re-use as long as the terms of its license are respected, without any explicit contact or negotiation between original author and licensee. Requirements vary from offering no restriction whatsoever to requiring that you credit the authors or that you also allow others to use your own derivative work freely.

The most common use of these licenses is for the original authors to inform other people interested in using their system that they are legally able to do so and even sell their own new work without having to pay anything to the original authors - however, even if those are intended as a gesture of good will and openness, failing to respect all of the terms from a license may leave you exposed to a lawsuit from the original creators.

Using an openly-licensed system for your own products (books, video games, card games...) means that you are able to rely on the work of others instead of having to design, write, playtest and balance your own. It also allows a product to become part of a larger community - which may draw those players (since they're already familiar with the rules) or allow them to combine your product with others that use the same system.

Here is a brief description of each major license found on the list below. Note, however, that details vary from license to license - so if you're planning on doing anything more than using the systems below for personal play, you should get acquainted with the full text of the license:

  • Open Game License (OGL): the OGL allows for differentiation between Open Game Content (parts of the system that others can use freely) and Product Identity (parts that are not open for others to use). Some publishers also create a System Reference Document (SRD), which is a version of the system containing only the Open Game Content, without any Product Identity.
  • Creative commons (CC): a family of permissive licenses that usually require only that you credit the original authors when using their work. Authors are free to choose from any of the CC licenses available - to read more about the differences between each, visit their official website.
  • GNU licenses (GPL and GFDL): designed for distribution of computer code and programs, this license allows you to use original work freely. However, if you are creating a modification of said work (for example, a set of alternative rules), you are required to make your own work available through the GPL license as well. If you are not modifying the original work, but only using it to create something entirely new (for example, a book with new characters and monsters to use) then you are not required to distribute it under the GPL. There are many versions of this license available, the most popular arguably being the GPLv2 - for more information about each version and related licenses see the official GNU website.

Some open games, despite being free to use and modify in derived work, require you to buy a printed book or PDF copy to learn the rules. The list below should only contain examples of systems that are also 100% free to acquire digitally - or at least allow you to look up most of the rules online.

Open Game License

Note that the official d20 SRD for D&D 3e has been revoked. It has been replaced by Paizo's Pathfinder SRD, which is compatible with previous d20 material and still being used for publication of new products by many companies and the community at large.

d20 System-based

d6 based

Fudge-based

Other systems

Retro-Clones

Retro-clones are new games that are compatible with older games now out-of-print, allowing for the use of previous material without having to acquire a possibly rare and/or expensive copy of the original game or resorting to piracy. These are part of a larger movement known as the Old-School Renaissance (OSR).

OGL with trademark license

These games release their material as Open Game Content but also provide another, more restricted license to allow publishers to refer to Product Identity.

  • Mutant Future (OGL and Mutant Future Trademark License)
  • GORE (OGL and GORE License)
  • FUDGE (OGL and FUDGE System Trademark License; also under its own license)
  • vsM Engine

Creative Commons licenses

Creative Commons Attribution

Creative Commons Attribution Share Alike

Creative Commons Attribution Non-Comercial

Creative Commons Attribution Non-Comercial Share Alike

GNU licenses

  • Gods and Monsters (GNU Free Documentation License)
  • Circe (GNU Free Documentation Licence and GNU General Public License)
  • Fringe (OpenOffice Writer format) (GNU General Public License)

'Copyright Free'

These works are generally free to be used commercially, without attribution, and without requiring derivative works be shared under the same licence (copyleft). Works are typically placed here because: 1. their copyright term has ended; 2. their author placed them into the public domain; or 3. their author gave them a licence that allows them to be used effectively as public domain.

Other licenses

External links