 In "The Sacrifice" DLC, any player, whether playing as Bill or not, can choose to sacrifice themselves to allow the other survivors to complete the campaign.In March 2010, Valve announced that it would be bringing the Steam content platform to Mac OS X computers; along with it, they will be providing native versions of existing Valve games including "Left 4 Dead" and its sequel.The game was released for Mac OS X on October 27, 2010 Left 4 Dead support cross-platform play, allowing Mac players to play alongside PC players on the same servers, and is also part of the "Steam Play" cross-compatible and Steam Cloud titles, allowing a player that has purchased the game on one platform to download and play it on the other platform for free.