Creating your own game elements

Some enthusiastic players of Spirit Island have asked whether it's OK to create their own Spirits, or other game elements like Scenarios, Power Cards, Adversaries, house rules, etc.
If you're just putting something together for your own copy of the game, that's obviously 100% fine! But what about sharing your ideas?

The publisher (Greater Than Games) has the following position:
Do what you like, so long it doesn't involve any of the following:
  • Charging money for it;
  • Portraying it as an official Spirit Island product;
  • Posting it on the official greaterthangames.com forums.
We will not under any circumstances look at submissions of such things, and will delete any posts on greaterthangames.com which contain them.

The designer (R. Eric Reuss) has the following position:
Please respect the publisher's desires.
I'd quite enjoy being able to peruse people's ideas for Spirit Island game elements, but have been advised that I only ought to do so when the creator of said ideas agrees to the following:
  • I am under no obligation to look at your ideas or to reply to your post/communication. (It can be fun, but life is often busy.)
  • You are owed no acknowledgement for your ideas, even if something similar, identical, or derivative is later published. (It's entirely possible that I was already working on something similar - parallel inspiration happens more often than you might think. And I don't want to have to track the source of every single idea I ever read online just in case it plays into some later idea I have; that's a lot of work!)
  • You are owed no compensation of any sort for your ideas: even if something similar, identical, or derivative is later published; even if your idea is acknowledged as a source or inspiration; even if you did lots of playtesting work on it. If relevant, you assign any and all rights / creative control over your Spirit Island ideas to me. (So I can run with them if need be. If you're not OK with this, I need to avoid reading your ideas so I'm not constantly second-guessing myself during development of my own ideas!)
This agreement is about ensuring people's expectations are realistic and that we're all on the same page. My understanding (though I'm no lawyer) is that the items above don't require an explicit agreement to be true (game systems aren't generally copyrightable; here's a neat paper about that)... but I want to avoid any misunderstandings or hard feelings!
So if you want me to look over your ideas - and I do love seeing people's creativity and joy in engaging with this world I've conceived of, even when I only have time for a quick skim - please preface your post / message with something like the following:
Eric: I agree to the terms for creating Spirit Island game elements set forth in the FAQ.
(Note the hyperlink to this page.)