How to Open License Your Game

January 30, 2010

Chris Sakkas (admin of the Year of Living Free wiki).

This is a draft. Do you have any suggestions? Email me at <>.

Why Go Open?

Why not? Let others build on what you’ve created, share your work and develop it further.

  • What if shoddy products reflect badly on my own? You can prevent this, most easily with the Open Game Licence. See ‘Product Identity and Closed Content’ below.
  • What if other people take my work and sell it? You can prevent this with a Creative Commons Noncommercial licence. See ‘Why Noncommercial?’ below.
  • What if other people adapt my work and don’t make it open? You can prevent this with a Creative Commons Share-Alike licence or the Open Game Licence. See ‘Why Share-Alike?’ below.
  • What if I’ve used other people’s copyright in my work? You can work around this. See ‘Legal Stuff’ below.
  • Will people use my material in a way I don’t like? It’s unlikely. I know of only one case where an author’s open work was used in a way that wasn’t appreciated. The author complained and the problem was resolved.

Benefits to going open include:

  1. It increases circulation of your game, because people know they can distribute it legally and ethically.
  2. Others may create supplements or modifications of your game, as people have for Donjon (Creative Commons Attribution Share-Alike) and 4C System (public domain).
  3. It allows you to give back to the community

You might prefer to read this article as a DOC.

Legal Stuff

  • Make sure you hold the copyright and trademark for your game

If you have used other people’s material in your game, you have three options:

  1. Ask their permission to release it under an open licence
  2. Remove it from your game
  3. Release the rest of your game under an open licence, leaving the stuff you don’t own as closed content (see ‘Product Identity and Closed Content’ below).

Which Licence?

  • I’ve used Open Game Content in my work. You must use the Open Game License.
  • I want or have to keep parts of my game closed. See ‘Product Identity and Closed Content’ below.
  • I don’t want derivatives to mention my name, publishing company or trademarks. See ‘Product Identity and Closed Content’ below.
  • I want people to use my material without any limitations. Release it into the public domain or use Creative Commons Copyright 0.
  • I don’t want my work used commercially. Use a Creative Commons Noncommercial licence. See also, ‘Why Creative Commons Noncommercial’.
  • I don’t want my work modified in any way. Use a Creative Commons No Derivatives licence. See ‘Why No Derivatives?’ below.
  • I want adaptations of my work to be open as well. Use the Open Game License or a Creative Commons Share-Alike licence. See ‘Why Share-Alike?’ below.
  • Otherwise, use the Creative Commons Attribution licence.

Product Identity and Closed Content

There are two reasons to keep content closed.

  • To release the rest of a game as open if it contains content you don’t own the copyright to.
  • To protect your name, publishing company and trademarks from being undermined by other people’s shoddy products.

Under the Open Game License: Either do not release the content as Open Game Content or identify it as Product Identity.

Under a Creative Commons licence: Include a comment like, ‘Most of this product is covered by a Creative Commons licence. The remainder (and explain which part this is) is proprietary and you must seek the permission of the copyright owner before using it.’

Why Share-Alike?

  • You are obliged to use it if you’re using material under a Share-Alike licence
  • Any material building on your own work is also open. Someone builds on your work, then someone builds on their work, and so on.

The disadvantage is that it can discourage people from building on your work at all. Some people are protective of their creations, particularly if they want to market them commercially.

Why Noncommercial?

  • It ensures that others can only profit off your work with your permission
  • It ensures adaptations and supplements are free, which support the community

I prefer to avoid Noncommercial. Give others a chance to make a buck or two.

Noncommercial can also get fiddly when someone wants to do something for free, but money is still involved. For example, a free podcast that makes some money from advertising. I used a Creative Commons Noncommercial image on a PDF I gave away for free. No problem. But then I wanted to release it as a print-on-demand book on Lulu at cost price. It wasn’t commercial for me, but it was for Lulu. I couldn’t do it.

I figure, my work will never make me a fortune. It certainly won’t make anyone else a fortune.

Why No Derivatives?

  • It ensures you control the nature and quality of any adaptations of your work
  • It stops others from undermining your product with adaptations of it or supplements for it

This licence is not open. It’s preferable to keeping the product completely closed, since it allows others to distribute your game, but it doesn’t fit the definition of open source.

How Should I Indicate My Work is Open?

  • It is simplest to put a note in the game itself. Creative Commons provides this text when you select a licence in a sidebar titled ‘Offline work?’
  • I’m not sure of the legality of a simple comment like “Creative Commons Attribution licence”. It’s better to stick with the official text.
  • I don’t think you have to include the text in the game itself. An announcement elsewhere, with the official text, should be enough.

Which Jurisdiction Should I Choose?

I believe Creative Commons recommends you choose as your licence’s jurisdiction the country where you live. They also offer an unported licence if you’d prefer.

What Else Should I Do?

  • Add your product to the Year of Living Free wiki or email its admin to do it for you
  • Consider making a System Reference Document – an HTML or DOC collection of all the open material, which makes it easier for others to adapt and reuse it.
  • If you’ve used a more restrictive licence, like Noncommercial or Share-Alike, tell people under what circumstances you’d consider a looser licence. (For example, ‘I’m happy to allow commercial products if you ask permission and give me a small cut’).

This work is licensed under the Creative Commons Attribution 2.5 Australia License. To view a copy of this license, visit or send a letter to Creative Commons, 171 Second Street, Suite 300, San Francisco, California, 94105, USA.


4 Responses to “How to Open License Your Game”

  1. […] wrote an article on how to open license your game, for those of you wondering if open licensing would work for you […]

  2. Mike Conway Says:

    I’m definitely in agreement with you on non-commercial licensing. Why the hell not let people make money?

    My belief is that generosity is going to become more and more of a trend, as people begin to look for more and more open licensed work.

    I feel that those who are most open with their work are the ones who are going to reap the most benefit. Right now, Kevin MacLeod of is a household name on the internet, especially for video makers who need free music. All of his music is CC-Attribution. He also creates music for a low-cost fee. But he’s very popular now, and I think that’s going to increase.

    Open licenses are also important to the longevity of a work. Keep it under copyright and then the means to contact you is lost, then the work will go into obscurity. I once found a game system I really liked, and tried to contact the author to no avail. By the time he finally got my e-mails, several months later, I’d moved on and used something that was open.

    Be generous, be happy for others to benefit off of your work, and the rewards will be great. That’s my thought.

  3. Jake Tober Says:

    This is the best summary I’ve seen so far. Maybe you can weigh in on a question:
    I’ve used Open Game Content in my work. -> You must use the Open Game License.
    What constitues “using” Open Game Content?

    If at some point in my life I read something written under Open Game Content and then later was inspired to make something else based on what I read. is that considered use?
    Considering D&D specifically: If I want to describe a character ability where a n sided polyhedron is rolled and as a result something happens is that using the d20 core mechanics? If I now call this ability a spell from a certain school? How about if another character can roll another polyhedron to change or avoid the effect? So much of the core mechanics are generic that could apply to any game, How much is too much?

    • sanglorian Says:

      Hi Jake,

      Thanks for your question. Although I’m not a lawyer and this is not legal advice, I’ll try to help.

      Copyright covers the expression of ideas. It does not cover game mechanics or ideas themselves. So using Open Game Content involves copy-pasting someone else’s OGC into your own work. Or copy-pasting it with a few words rewritten (or even the whole thing rewritten, if the rewrite uses a lot of the same structure, language and that sort of thing).

      So if you were simply inspired by D&D to make new game mechanics, that should be legal. Even using the exact same mechanics as D&D should be legal. Once you start using WOTC’s expression (whether verbatim or otherwise), that’s when you start running into problems.

      I hope this helps. Let me know if you have any further questions.


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