Are you talking about patenting a gameplay idea? They aren’t very effective, basically impossible to enforce, and aren’t going to completely stop being ripped off. Also completely original gameplay ideas are rare these days.
Copyright automatically applies to anything you make in the US even if it’s unpublished. If someone is ripping off your characters, music, etc, it’s pretty straight forward making a copyright claim. But remember that other people are allowed to have things that look very similar to yours without it being copyright infringement.
There is no way to do so. Your best bet is creating the game and don’t show it to anyone until it’s 2-3 months until release, that way noone can copy your concept and come out earlier. Happened to me once, since that i don’t show or say anything until i have the product in shape. I built the prototype to ARK, showed it to Microsoft to release it on XB1 and 1 month later some of them left MS and created ARK. Game died with the release of ARK.
If he had created that, AND he had created code and assets, AND they had taken some of his code and assets, then that might be true.
However, if they did not use his code and assets, and the similarity is more like “this is a survival crafting based game” or whatever, then there’s no claim to be made.
Ideas are a dime a dozen. Literally – everyone has more ideas than they have time to implement, and all of them are potentially good.
It’s execution that matters. A good idea with terrible art, buggy code, and no marketing, will go nowhere.
Similarly, you can’t copyright or patent or trade mark movie plots, or book plots, or song structures. (“Yeah, I have a patent on DROPPING THE BASS! You guys, pay up!”
And, very likely, the reason you came up with some idea, is that you were exposed to certain events, media, and experiences.
It turns out, other people likely have similar experiences, and thus will likely come up with similar ideas, all on their own.
The best thing you can do is JOIN WITH THEM and together perhaps you can actually EXECUTE and make the game idea, a reality.
Secrets don’t build anything. The only way to find people who can help you, is to share your ideas and enthusiasm.
If you think that your idea is a special snowflake that has value just by being an idea, without having any of the execution to go behind it, I recommend reading this reference: