Mac and PC players who own Left 4 Dead 2 have been given a little treat: Cold Stream. It's a new, free, work-in-progress campaign being made by modder Matthew Lourdelet.
While this is still in the beta phase, it's shaping up nicely already. A perfect excuse to jump back into Left 4 Dead, if you've neglected to play in a while. Perhaps I'm just rusty, but there's some challenge to be found here. Those infected aren't kidding around.
Cold Stream is also going to make it onto Xbox 360 eventually, but that'll be the finalized version.