Copyleft works can be shared both in original form and after being adapted, but they must remain under the copyleft licence even if they are modified.

Copyleft licences are also called 'reciprocal', 'viral' and 'share alike' libre licences. However, whereas copyleft can only describe a libre work, the other three terms can also describe proprietary works that must be kept under the same (proprietary) licence when adapted.

Openness: Libre


  • XochitlcozamalotlAztec daisies, god-rabbits and divine parties meet in this Aztec soap opera.
  • YagsA moderately crunchy cinematic rules system.
  • Yanone KaffeesatzThe first font completed by Yanone.
  • Ye Olde Adventure ShoppeA proof of concept for an HTML5 game for the Liberated Pixel Cup.
  • Yo Frankie!A computer game where you control a rodent.
  • YorokobuA Spanish language magazine about innovation, inspiration, trends, sustainability and the adventures of entrepreneurs.
  • You All Meet In A Tavern'As a fledgling adventurer you have decided that the best way to get into the business is by attending the monthly Adventurer-Nite at the local White Griffon Tavern.'
  • ZeFRSA retroclone of TSR's Conan RPG.
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  • Basic Dungeons & DragonsThe mechanics of original and basic D&D.
  • CC-PROA rebranding of the CC BY-SA licence to emphasise its value to professionals.
  • d20 SystemThe roleplaying system which first appeared in Dungeons & Dragons 3E.
  • FATEA game system based on the mechanic: dice roll + invoked and tagged Aspects.
  • Liberated Pixel Cup"Liberated Pixel Cup is a two-part competition: make a bunch of awesome free culture licensed artwork, and then program a bunch of free software games that use it."
  • Saga Machine'Saga Machine is a brand new tabletop role-playing system by the Tab Creations Collective.'
Unless otherwise stated, the content of this page is licensed under Creative Commons Attribution 3.0 License