Crash Course delivers new single-player, multiplayer and co-operative gameplay and bridges the storyline between theandcampaigns in the original game. To celebrate, we are offering Left 4 Dead at 50% off for 3 days. Or share the fun - get the Left 4 Dead Four Pack and give the game to your friends.While containing both Survival maps and a Co-operative Campaign, the primary goal of Crash Course is to deliver a complete Versus mode experience in just 30 minutes, resulting in a streamlined version of the game's existing Versus campaigns.Learn more about the free, all-new free Crash Course DLC on the Left 4 Dead Blog