Just checked this out on YouTube.
It's downloadable on
http://www.hidden-source.com/What I've seen is kinda like the versus mode in Left 4 Dead but it's more like an awesome horror movie.
Damnright awesome if you play it with skype/teamspeak in the middle of the night.
Example video by EatMyDiction1:
It's so awesome seeing the friend dots on the map disappearing one after the other.
