Abandoned and alone in a city infested with zombies, you have no hope for survival. The feeling of being surrounded but isolated is what most zombie/horror stories, movies, and games go for. Yet, in many stories there are at least some other human survivors (for awhile). Left 4 Dead centers around this aspect: the teamwork to survive. However, in a traditional zombie movie, four CounterStrike counter-terrorist agents would have little trouble surviving. Something has to be done to make the game challenging for the people who are already excellent at games like Halo or Team Fortress 2.
That something is the endless horde of 28 Days Later zombies.
