For whatever reason (most likely an unprotected or hacked SWF), your game is sitting on another server illegally, and you want it removed. Here are some things you can do.
Email the Webmaster
Almost all Web sites have a "Contact" or "About Us" page. On one of those pages you're most likely to find a contact email address. Write something like this:
Email or Call the ISP
If you get no response from the Webmaster, you can involve the site's Internet service provider (ISP). I have contacted the ISPs of more than a dozen Web sites to have content removed and find it very effective they don't want to be associated with any illegal activity and are quick to take action. Here is how you find out the ISP of a Web site.
You may see personal information about the owner of the domain (such as phone number and address). Toward the bottom you will see information about the domain servers and that's how you find the site's ISP. For instance, if NS.MEDIA3.NET is the domain server, then www.media3.net is the ISP. You can then visit the ISP's Web site and contact the ISP by phone or email.
Here is an actual letter I once wrote to an ISP after days of ineffective letters to the Web site's owner.
The matter was resolved in under an hour after I sent this!
Take Legal Action
Happily for me, this is something I haven't experienced. Every letter to an ISP has been effective. However, some day you may encounter your content on a Web site that is its own ISP (or has some other reason for not removing the game). In this case, look in the phone book (or on the Internet, of course!), or start polling your savvy friends, for an attorney specializing in Internet law.