I think that you may be going about this the wrong way.
If you are wanting monetary compensation from GS for intellectual work, I truly believe you should contact the studio directly and apply for a job or solicitate your consultation services. I could be wrong, but I do not think that there is a precedent for hiring an unverifiable person from a forum off of a promise of an idea. I believe you said you had experience in the game creation industry, this will help greatly.
If you believe you have a multi million dollar "Idea" that would work for any game. Well then my friend, you should take your industry experience and your idea and go make a game and get that paper. Don't even let a terrible studio like GS get a chance to fuck it up.
If you believe in this game and want to improve this game with your ideas, then you should get on the public game forums and discuss them in detail. Get enough positive feedback and it will most likely get implemented in some way shape or form. However you will be the only person that knows it was your idea. Maybe some of us will know as well.
Keep in mind that GS hasn't released any games yet. They likely have not turned any profit. Their team is small, and greatly lacking in talent when compared to almost any other game studio out there. What they DO have is a lot of ideas that sound really cool. What they DONT have is any proof that they can carry these idea through to fruition.
I will give you my personal view on this. Ideas in and of them self are not worth anything. Even after being shared with a group and refined into a better idea, it is still not worth anything. Money is only made when an idea is acted upon and a product is produced and sold successfully.
So let me ask you. Do you really have an idea that these guys can do anything with? They have yet to implement their own ideas in a profitable way.