Left 4 Dead feels a lot like the spiritual descendant of the Resident Evil: Outbreak series of games. For the most part, it's a cooperative survival horror game, hopefully without the weird feeling of running around with a broken broom like the above-mentioned Capcom game. Unlike Resident Evil, though, the design of this game is definitely Valve's specialty: Counter-Strike style.

At least, that's what Michael Booth of Turtle Rock Studios, the developer of the game, says of it. As he mentions in a GameSpot interview,

Like CS, the design goal is to create interesting areas that will allow for extended replay value. Unlike CS, the maps in each campaign are connected and lead to an eventual finale that the survivors are challenged to reach and complete. And along the way, player stats are collected and displayed at given intervals.