Left 4 Dead is a cooperative survival horror first-person shooter video game. It was developed by Turtle Rock Studios, which was purchased by Valve Corporation during development. The game uses Valve's proprietary Source engine, and is available for Windows, Xbox 360 and Mac OS X. Development on the game was completed on November 13, 2008, and was released digitally on November 17, 2008, and at retail on November 18, 2008, in North America, In Australia on November 18, 2008, and on November 21, 2008, in Europe and Japan.
Left 4 Dead was well received by the industry media upon its release, with praise given for its replay value, focus on cooperative play, and movie-like experience. Several criticisms were aimed at limited level selection and the lack of a narrative. The game has won several publication awards, as well as distinctions from the Academy of Interactive Arts & Sciences and British Academy of Film and Television Arts. As was done with Team Fortress 2, Valve plans on supplementing the game with free downloadable content. The first of these, called the Survival Pack , was released on April 21, 2009. The second piece of DLC was charged for via Xbox Live and came in the form of a new Campaign entitled Crash Course, released for both the PC and Xbox 360 on September 29, 2009.
The popularity of the game led to the development of a sequel, Left 4 Dead 2, which was released November 17, 2009. Left 4 Dead 2 was released on Mac OS X via Steam on October 5, 2010, and the original Left 4 Dead was released for the Mac soon after on October 28, 2010. The Mac version of Left 4 Dead 2 incorporated a new map for both Left 4 Dead and Left 4 Dead 2, called The Sacrifice, as well as No Mercy being imported into Left 4 Dead 2, allowing for cross-platform support between PC and Mac versions.
The artificial intelligence of Left 4 Dead features a dynamic system for game dramatics, pacing and difficulty called the Director . Instead of fixed spawn points for enemies, the Director places enemies and items in varying positions and quantities based upon each player's current situation, status, skill and location, creating a new experience for each playthrough.[10] The Director also creates mood and tension with emotional cues, such as visual effects, dynamic music, and character communication.[11]
