IGN: Left 4 Dead Versus Mode Hands-On

At its core, Valve's Left 4 Dead isn't a complicated game. In its main cooperative mode you play as human survivors who must, using bullets and teamwork, overcome hordes of swift "infected" (zombies) and reach the end of a more-or-less linear stage to escape. The survivors are then graded on their performance, and onto the next stage you go. That's pretty much it in terms of basic structure, but Valve's added in plenty of wrinkles to make it interesting, including split-screen offline and online co-operative modes for the Xbox 360 version.