In this game, you have the choice to play as one of four individuals. You can choose Francis, a tough looking biker with lots of tattoos. Or you can play as Louis, an IT geek who is out for a stroll among the zombies. Then there's Zoey, a college girl who enjoys horror movies. Finally there is Bill, a Vietnam veteran who brings battle experience to the team. It doesn't matter which one you choose, as they don't have different abilities or anything. They do however, each have a unique personality. In the single player game, you get to hear their vocalizations at various moments and it definitely adds to your immersion into the game.
Unfortunately, there's really not much storyline here. Other than a cinematic entrance, all you know is that you and these three other individuals are trying to survive without being torn to pieces by the zombies. There is no explanation for how you got there, and there's no story for why there are zombies everywhere - let alone why some of them have superhuman abilities. This can be either a good thing or a bad thing, depending on your perspective. If you are looking for a detailed story explaining how you got to point A and why the world has gone to hell-in-a-handbasket, you won't find it here. If however, you want to join some friends online in a team of four and systematically blow away zombies, Left 4 Dead is sure to satisfy. There are clues regarding a backstory, but its very hit and miss. The mystery that usually surrounds this type of genre is alive and well in this game, but the absence of a story doesn't really detract from the experience as much as you might think though. Perhaps in an expansion or add-on, they will fill in the gaps.