i read this article at Games Are Fun about all the rampant German censorship that's imposed on video games there, so i find it odd that they would hold such an event there.
While it's true that German games get censored a lot (you won't find stuff like Return to Castle Wolfenstein in there), that doesn't mean that a convention dedicated to gaming itself cannot be held. Neither the music nor the convention itself really emphasize violence in any way, so I don't think the two are really that relevant.