As if the recent announcement that the upcoming Left 4 Dead DLC will be offered for free wasn't enough to tempt gamers into some zombie shooting action, Valve has sweetened the deal by offering the popular game for half its normal retail price on Steam. This is valid for the PC version of the zombie co-op shooter, of course, and puts the game at a tempting $24.99 for this weekend only.

On top of the incoming "Survival Pack" expansion, owners of the PC version can also expect the long-promised SDK at some point, which should allow for the creation of custom maps, scenarios and other mods. Still not convinced? Check out a couple of reviews at GameSpot and IGN to help you decide.