If you get into trouble you might be able to get help from someone at
NewMediaRights.org
Unfortunately there it is extremely easy to clone a game and avoid any copyright issues since copyright only applies to audio/visual assets. So just clone a game's mechanics and key features and make new assets and they're not really infringing on copyright. Similarly with patents. Not only is it extremely difficult to patent software, but more than likely the methods you use in your game are not even eligible for patent. Not to mention it can cost around $10,000 USD to hire a patent lawyer and years to get approval.
http://www.gamasutra.com/view/feature/1735/the_ten_most_important_video_game_.php
Some new methods that are arising are more in the form of social blacklisting. If someone steals your idea you can take it to Reddit and there's an army of people who may support you and boycott the other developer. You had better be sure that they're copying you though because they can potentially sue you for ruining their game as well.
And it can lead to flame wars like this:
http://kotaku.com/developers-accused-of-cloning-luftrausers-say-luftrause-479916446
Gamasutra has a lot of articles on how to protect your game, combat piracy, and other very topical things. Also Kotaku does a lot of coverage on these types of things, but they seem to be a bit of an instigator.
In today's industry you have to do the best to make a name for yourself and be known. Do what you can to get people on your side so that your idea is recognized as your property. At the same time plan your game so that you can quickly build in new exciting features or mod the game like Angry Birds has done. You essentially have to be ready to be at least one step ahead of your competitors.
In this respect, cloning may not necessarily be a horrible thing. Does it completely suck and is it completely unethical? Yes! But what is evolving from it is a new generation of game development where we have to be on top of our game, we have to be ready to release new features to our game shortly after it is released. Ultimately that will create better games, but in the meantime it is a cutthroat industry.
