Valve has announced that the popular co-operative zombie shooter, Left 4 Dead, will be available as a free trial for PC gamers beginning Friday at 12:01 AM GMT for 24 hours. The offer includes full access to both the original game’s content as well as the recently released Survival Pack, which introduces a new multiplayer survival game mode and two additional versus campaigns; Dead Air and Death Toll.

Those interested in the offer will be able to pre-load the game right now with no obligation to purchase; that way users can avoid wasting a chunk of the free 24 hours downloading the title. Once the trial is over, free versions of the software will be locked, and gamers who wish to continue playing will have to buy the full version for $39.99. If you’ve been holding out on buying the game, here’s the chance to play and decide if it’s worth your hard-earned money. More details are available on Steam.