Watch Dogs is a new video game set in an alternate reality Chicago where everyone and everything is linked through a central network—like something out of a sci-fi film. To promote the game, marketers developed real versions that pull together mountains of data about Paris, Berlin, and London—and the effect is fairly chilling. The experience is helped along by moody visuals, atmospheric music and interesting sound effects, sure. But that doesn’t stop the real-time visualization of everything—from underground trains, through electromagnetic fields and traffic lights, to social media updates—seem any less interesting or creepy. Go explore one of the cities—it’s really quite compelling.