publish work under CC BY-NC
<p>I have been creating a rpg system for the past few years, and I wish to put it online for the world to see, use freely, propose modifications and create with it as an inspiration.</p>
<p>As I wish to later publish it commercially, with additional content on the side, I was looking on a way to license it in a freely but not to freely way.</p>
<p>The CC By-NC-SA seems like it fits what I'm trying to do, but I have a few questions.</p>
<ul>
<li>
<ol>
<li>As the person imposing the license, could I still at a later date publish that work commercially?</li>
</ol>
</li>
<li>
<ol start="2">
<li>If yes, could I include the modifications that were proposed by others to that publication (with citation of the person's name and the way they helped, of course)</li>
</ol>
</li>
<li>
<ol start="3">
<li>If I'm having a company publish that work for me, how would the license affect it?</li>
</ol>
</li>
</ul>
<p>I'm aware that this question has similar answers already, but what I found did not make things clear for me.</p>

<ol>
<li><p>You can't withdraw the license (<a href="https://creativecommons.org/licenses/by-nc-sa/3.0/legalcode" rel="nofollow noreferrer">clause 3</a> says &quot;perpetual&quot;), but apart from that there are no restrictions on what you might do with your own work.</p>
</li>
<li><p>It depends on whether the proposed changes rise to the level of a separate or derivative work. If someone suggests &quot;I think you should have orcs in this&quot; then you have no problem. But if someone sends you an orc character class with text and tables to drop into the system, or a modified document file containing the same, then they have copyright in that work and you need a license.</p>
</li>
<li><p>That would be a commercial matter to discuss with a publisher. Most publishers will want a limited period of exclusive rights. If your game system is already floating around the net with a permissive license then you can't give them exclusive rights, and that is going to harm your negotiating position.</p>
</li>
</ol>

licensing creative-commons