The Malthusian Paradox is an ARG, or rather “An immersive transmedia narrative experience, played out online and in real life” that is currently is running in Nottingham – have a look here http://malthusianparadox.com/?p=208.
The project uses a couple of Polargraph machines, along with Adam Sporne’s exciting Drawnomic machine in it to reveal, slowly some clues – I’m excited to see how it turns out!