Developer: Valve Platform: PC, Mac OS X, Xbox 360, Linux Release: 2009 When Valve announced that the secret project that they'd been working on for years was actually a co-operative, multiplayer zombie shooter rather than something more Gordon Freeman-related, there was a slight air of disappointment. Concerns turned out to be totally unfounded though, when Left 4 Dead emerged to be one of the most frantically fun co-operative experiences ever. Left 4 Dead 2 was released around a year afterwards, and the series once again found itself in the centre of controversy, with many fans threatening to boycott the title due to its release being so soon after the first title. The sequel received even more positive reviews than the first game though, with improved AI, a greater variety of enemies, and more interesting environments.
