A few years back (2013?), there was an ARG that turned up at PAX. One of the booths just had a bloody computer monitor in it that played clips of what seemed to be people getting murdered by an assailant in a doll mask. No one knew who had set up the booth, although there apparently was an association with the team behind Super Meat Boy.

There was a Twitter account under the same name, along with a site, which seemed to feature some of the expected ARG content (e.g. stuff hidden in the site code), and at one point, certain followers were sent pieces of an image that, when put together, formed a poster.

From what I can tell, it never really went anywhere, and hasn't been active for a while, but I'm still super curious about what it was all about, and would love to find some info about it!