Welcome to the forum!
When you put it up a game on steam for multiple regions not only do you need to know how your own legal systems works, you have to know the offenders legal systems to even enforce either your copyright or intellectual property.
It is a very complicated topic that a Lawyer specific for game markets would know best.
From my limited knowledge of copyright I know that you cannot copyright a general idea such as a RPG or FPS. You can copyright written code, art, music, your specific story, etc.