Left 4 Dead 2
Left 4 Dead 2 is the second release in a series of zombie horror/survival, first-person shooter video games, published by Valve Corporation. It was released in November 2009 and is available on the Xbox 360 and PC. In February 2010, distributor Electronic Arts announced the game has sold over 2.9 million copies worldwide. . Like its predecessor, the gameplay centers around four survivors caught in a zombie outbreak, trying to survive and ultimately escape.
The sequel picks up one week after the events of the first game ended, and the zombie pandemic has spread to the American South, including New Orleans and Savannah, GA.  Gameplay is mostly similar to the original Left 4 Dead. Campaign, Versus, Survivor, and single-player modes still focus on four survivors caught in the middle of the zombie outbreak and trying to escape safely. (For more information on these gameplay modes, see Left 4 Dead > Gameplay). Left 4 Dead 2 introduces four new surviving characters, five new maps (with more available via downloadable content), several new weapons, and new boss zombies. Also added is Scavenger Mode, a new multi-player versus mode, where survivors try to collect and use materials needed to survive, while player-controlled infected try to stop them. 
Left 4 Dead 2 includes an improved implementation of the Left 4 Dead AI Director, allowing the "Director" expanded ability to customize level layout, world objects, weather, and lighting to reflect different times of day. 
Valve received heavy criticism when production of Left 4 Dead 2 was first announced, due to the fact that the sequel would be released within a relatively short timeframe after the original Left 4 Dead.  It was ultimately released exactly one day short of a year after Left 4 Dead. This led to several concerns among the gaming community, including:
- the release of a sequel splitting the community and decreasing the quality of multiplayer gaming
- the original Left 4 Dead not receiving content updates which Valve had previously promised
- the content of Left 4 Dead 2 not being enough to warrant a stand-alone, full-price release, and instead should become an update (free or not) for the original.
- The release of Left 4 Dead 2 making Left 4 Dead an obsolete purchase only one year after release
These concerns led to fans organizing boycott groups on Steam (Valve's online matchmaking and community service), pledging to boycott the sequel.
Despite the concerns listed above, Left 4 Dead 2 released to strong initial sales and generally favorable reviews. To Valve's credit, they have continued to support the original game with updates and new content, eliminating one of the major concerns behind the sequel's release.