Feeling like you missed out on Left 4 Dead, especially with all the buzz surrounding the new Survival Mode that was added to the game last week? Valve"s got your back. A free trial of the co-operative zombie shooter will be available on Steam starting this Friday at 12:01 a.m. GMT.

Similar to Team Fortress 2"s occasional free weekends, the trial version of Left 4 Dead will apparently include full access to both the original game"s content as well as the Survival Pack, but will only function for 24 hours without actually paying for the game. Interested parties can (and probably should) begin preloading the trial right now -- that way Bill, Louis, and the gang will be ready to tackle the undead apocalypse the moment this thing goes live.