*Note* I will try to keep this write up spoiler free for those of you who have not had a chance to run through it.

I fired up Steam where the content is free (560 points if you play on the New Jersey of online gaming XBL) and loaded up the single player campaign mode to blow through as fast as I could. We all know that single player forces you to use bots, which is not the best way to do it, but new levels full of the undead wouldn't wait for my crew to get out of work. Hence I journeyed back to the dirty south to lower the indigenous population one frying pan swing at a time.

There is nothing too revolutionary about the new campaign. It flows well and definitely is up to par with Valve's pedigree of solid level design. It has a distinct aesthetic appeal while at the same time feeling friendly and familiar (as the zombie apocalypse should). The survivors from the first Left 4 Dead do make appearances, but do not play a pivotal role in changing up the zombie massacre we have all become accustomed to. In terms of the PVE side enjoy more high level of first party content but don't expect a whole new experience.

The biggest innovation you will find in this package is Valve's new "mutation" mode. Valve is using this feature to implement new gameplay types, changing weekly, to keep the limited maps feeling fresh and giving people new ways to play through the same campaigns. Every week will feature a new set of rules and at the end of the month the community will vote on which mode they like best which will be made a more permanent feature. While this is cool why not just introduce all the modes you have planned and let us decide if and when we want to play them?

Bottom line is that for free (for us belonging to the superior PC Master Race), or for a nominal Microsoft tax Valve has provided content that will not change any of the mechanics, but add some more miles to the formula you either love or hate. It won't win over any new fans, but those of us who spend too much time murdering zombie after zombie, its more of what we love.