I've thought about this topic as well and have a few things to keep in mind. These are only my opinions and semi-rational observations, so take it with a grain of salt.
- do some research before publishing a game to see what's on the market (title, content, etc); try to be pro-active so you don't step on any toes.
- someone is going to copycat your work, especially if it's popular (look at all the minecraft knock-offs); in the age of hyper-fast always-on media, there's no avoiding it. Try to get your product out to as many places as possible and maybe awareness will help dilute some of the copying.
- as for piracy, I'm not sold that anti-piracy/DRM is the way to go. It makes it harder for casual users and honest customers unless you have a real top-notch service handling it (like Steam, which still has issues). If someone wants the game bad enough and they're skilled enough, they'll find a way to steal it no matter what you do; adding extra layers of security is, in my opinion, just introducing more headaches and hurdles.
- I have no idea how copyright / IP laws work in Europe, but in the US the copyright is assumed upon the first creation of a work. Registering the work ensures there is a public record that can hold up in court, but it is not necessary to claim copyright. Obviously if the project is a money-maker and turns out to be popular, registering ownership can't hurt.