Left 4 Dead 2 CD Key is a shooter cooperative first person game and is “Left 4 Dead’s” sequel. It was released on 17th November 2009 in the U.S. for Xbox 360 and MS Windows and in Europe on 20th November 2009. Mac OS X was available to Steam client on 5th September 2010 and 2nd July 2013 for Linux via Steam. The game had been released as free download by Valve for all users of Steam on 25th December 2013 for 24 hour period.
The background of the game has been set after the apocalyptic pandemic took place, with the gameplay focusing upon four new survivors, who try to fight against the infected hordes that exhibit features like that of the zombies. The gameplay has five campaigns, which the players are to complete and their objective being to escape to safe houses, which acts as checkpoints. AI Director 2.0 is said to have the players’ performance to be monitored and gets the scenario to be adjusted for providing dynamic challenge, thereby altering the gameplay procedurally. The other new features of the game are said to include special infected types and melee weapons of different types. It was at the E3 2009 that the game had its world premiere.