Offering it on the net to anyone who is interested, without buying the game for example.
You don't have to offer them the game - just the source code. You're telling me that the average match-3 gamer is going to have the technical savvy and determination, to go to the process of finding suitable replacement media, compilers, and whatever else you need to make a game, besides the source code, just to save 10 bucks?By your "argument" you couldn't make any money on closed source games either, because someone could just write their own game instead (ala. Grid Wars). Now if Grid Wars was GPL'ed, it's questionable that Bizarre Creations could have "shut it down" so to speak.