I'm currently developing a game for which I want to document my experience with online through my website. On the site, one of things I want to offer anyone who subscribes to my mailing list is access to my sourcecode repo via github. Basically, I want them to be able to play around with my source code for their own personal, educational use while learning through my site. I'm currently planning to release the source code under the Attribution-NonCommercial-NoDerivatives 4.0 International license which does not allow any modification or redistribution of my game without my permission.

My question is when dealing with software, at what point is it considered illegal to use a certain algorithm or solution to a particular software problem? Or a particular video game idea? For example, say someone on the comment section on my site offered a coding solution and/or an idea for my game for which I implement. Or say I used a coding solution from a blog I read and later the blogger recognized, from my github repo, his solution was used in my game. If either of these people decided to come back and sue me would they have any legal grounds to do so?

  • "I'm currently planning to release ... under the Attribution-NonCommercial-NoDerivatives 4.0 International license which does not allow ... redistribution." - This is incorrect. CC BY-NC-ND specifically allows redistribution under the agreed terms.
    – Brandin
    Sep 7, 2018 at 6:22

1 Answer 1


As far as copyright is concerned, you can use anybody else's ideas and solutions, you just can't copy their code. Copyright protects expression, not abstract ideas. That does not mean that there is no possibility of being sued by someone else. For example, suppose you learn of the notion of a "bubble sort" in reading Smith's code, and write your own routine. By it's nature, your code will resemble Smith's to a certain degree, so having that kind of similarity would not prove copying. On the other hand, you could copy 2,000 lines of code and change the names of variables -- the result would not be exactly identical, but it is impossible that you got only the abstract idea and then independently recreated those same 2,000 lines except for some renaming.

As for comments, note the TOS under Contributions Under Repository License.

Whenever you make a contribution to a repository containing notice of a license, you license your contribution under the same terms, and you agree that you have the right to license your contribution under those terms. If you have a separate agreement to license your contributions under different terms, such as a contributor license agreement, that agreement will supersede.

Isn't this just how it works already? Yep. This is widely accepted as the norm in the open-source community; it's commonly referred to by the shorthand "inbound=outbound". We're just making it explicit.

So if you attribute and do not change, and make no money, then code from comments can be copied. But ideas can be freely exploited regardless of your license. You would need to be careful to not accidentally copy code from a comment.

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