A while ago when discussing the release of the Quake3 engine as GPL, someone said "if you release your source code as GPL then someone can grab your code, recompile it, and offer a download that includes his binary and your freely distributable demo (or a link to it) which contains the assets, and sell it legally". That got me thinking. You don't need the code to be GPLd to do that! For example, games by PopCap have their resources in a folder. So what stops people from just reimplementing the game from scratch, using all the assets from, say, Bejewelled? You have all the content (which is the hard part in a Match3 game, right?), you even have the gameplay, it's like having a dream design document - you can actually play it! No, I'm not planning to do this. It's just a theoretical question. What do you think? Is this the definitive argument against leaving your assets unprotected?