Bummer man. For real. I've had a lot of music stolen, but not a game. Like people have been saying, if you have the original files (artwork, sourcecode, music), you'll be in a great place to issue a cease and desist notification on anyone who shouldn't have it. Get a lawyer to draft up something professional but threatening.
That's the nice sugar coated version.
The nasty reality is, that if it's posted all over the place, the most addictive dopest game in the world, and hosted anywhere in Czech Republic...you're screwed. Encryption, site-lock, and watermark are your friends, but even they are mild deterrents to the truly dedicated and talented pirate.