Do I lose author rights if I make the rules available online?

Concepts cannot be copyrighted, just text and artwork.

So no, you don't lose any 'author rights' by publishing something online; you don't gain any rights by not posting it online, either.

There is no contradiction. Your work (graphics, text) is automatically protected. Your idea is not protected.

I don't think there is any legal reason for them to ask for permission, but they do it to keep good relations with designers, and because the publisher is likely to need many hours of work from the designer to complete the game anyway (it will probably be more expensive to pay someone else to figure out all the details of your design and complete it). The publisher is likely to pay for all the graphics and rules writing, so they will own all the copyrights (unless they share them with you as part of signing some contract; not sure how common that is). Also if your idea is that good, the publisher will want you on their team, making new great games for them.

As for anyone here stealing your idea, I think it is safe to say that everyone here has at least 10-100 great ideas in their backlog, and no matter what your idea is all of us will think "nah, I have 5-50 ideas better than that I work on anyway, why bother?". So many great ideas out there, and until your game is already published and a big hit, your biggest risk is that no one will look at your game, not that someone will steal your idea (although of course there is always a risk).

Also, we can help you point at similar games to your idea, which will help you in completing the game and someone is likely to give you good feedback that will help you improve it. It is difficult to get that without talking about what you have.

Have seen many, many threads like this one in the last 10 years on this forum and on bgg, and almost every time the new designer decides to not reveal his fantastic new idea. Then I never hear about that designer or game again. I doubt more and more that secrecy is a good strategy.

The risk of no one knowing about your game is much more probable and 'severe' than that of people stealing your idea.

What I meant by "you don't gain any rights by not posting it" is this: if you post something, people might copy your idea. If you don't post anything and then start selling, people might still copy your idea. Also, if you don't post anything, people might have a similar idea and talk about it before you do, making it seem like you copied *their* idea (when in reality, no one copied anyones idea c.q. everyone copied everyone else's idea).