I am curious about what process should be followed to protect a game in general. I mean for example suppose I create a unique game and post it to the projects forum. Then someone else saw it and thought, 'oh that's pretty cool, only I could do it better' and then takes the same idea but makes their own version and then ends up selling it. Or, suppose I finish my game and decide it's commercial ready and start selling it. Someone sees the commercial version and decides to make their own version but using the same ideas or story line etc. What is the standard process of copyright protecting against this type of thing? Is it something to be concerned about in early stages of game ideas or just in the final stages of game completion? Is it expensive to protect or worth it? Also, what ways are there to do it?

Thanks.