As an unpublished indie, I wish you the best of luck signing a 2-way NDA with a major international publisher. It's probably not going to happen, until they see something they like from you, and draft up a real contract. Publishers generally get so many different submissions that the last thing they want to do is sign a piece of paper that could lead to an indie sueing them for making 'a game just like mine'.

You also seem to be under the misunderstanding that you don't 'own' the rights to your own game anywhere but Chile. This is wrong; your copyright extends beyond your home country, and a professional company wouldn't dream of ripping you off. It's not worth their time.

It's a different matter if there's some irregularities attached to your IP; for example if you're using a license (StarWars, StarTrek, etc) that you don't have the rights to, or if there's something fishy about the contracts you've signed with your day-jobs. In that case, the publisher will most likely walk away.

While the good, american, answer is 'consult a lawyer', I understand that for indies outside of US, finding an IP lawyer with understanding of US IP law is hard (and costs a bomb).

Best of luck,
Allan

Focus on developing something first; the lawyers will happily tell you that they need the money to feed their starving kids, but reality is that unless you have a product, the legal advice isn't worth the pretty papers you'll hand over to get it. If you can find a friendly lawyer WHEN you have a contract in hand, it might be good, but until then save your money.

Registering copyright is a no-brainer; and in most cases you don't even need to do that (just keep Work in progress, etc, to prove you actually developed the titles). No reputable publisher of mobile games will try to pass your game off as their own, and your copyright remains valid even outside of your native country.

Someone else posted that you'd best make sure the publisher signs a 2-way NDA before you show anything. For most developers that's not an option; publishers don't want to leave themselves open to this sort of nonsense:
http://www.gamesindustry.biz/content_page.php?aid=13397

It'll be interesting to see what will happen to US patent and IP law in the next 10-20 years; the current situation is effectively killing the R&D industry. You gotta love this quote from the CEO of the US Chamber of Commerce:

"U.S. industry spends more on tort litigation than on R&D…just think about what that says about our nation’s priorities and the challenges we could face in the future if we don’t reorder those priorities."

http://www.uschamber.com/press/speeches/2005/051102tjd_latownhall.htm

As such, the advice to consult a lawyer makes a personal kind of sense, but ultimately just feeds the monster hiding beneath the bed.

Allan