Given that it's a GOG the current rights holder is listed as the publisher on the game's page. For instance the publisher of Last Express is Phoenix Licensing, who obviously had no hand in originally publishing the title. So it shouldn't be so difficult tracking down the rights holder.

Beyond that, simply giving copies of your work to either a solicitor, bank or building society would go some way towards protecting it as they'd be able to support your claim to being the original author as the date you gave them copies would be recorded.

So you plan to propose ideas and don't want to get ripped off? It sounds like what you want is an NDA. Consult a lawyer - it's pretty standard stuff so it shouldn't cost too much. Make sure that the agreement you bring for the interview is short and straightforward, otherwise you won't get an interview at all.

He's on IRC more often than not so lurk there and when you see him drop a line.

He looks through the users @ gog email. So if you title it with his user name you'd be better guaranteed a response.

It's highly unlikely that you'd be able to get a patent on a rule system (the most common test of patentability is the machine or transformation test). Additionally, patents are not free to get, and also require quite a bit of work to be put into putting them together if you want them to be worth anything if the matter makes it to court. You'll need to pay filing fees when you submit to the patent office, and likely wait a couple of years while they get around to reviewing the patent before you even know if they intend to issue the patent or just tell you to get lost. Basically, unless you plan to be making some serious money off of this then it's not worth the time and money to even try to get a patent, even assuming that your ruleset is patentable (which is a major assumption).