If the actual Left 4 Dead is a little too frantic for your tastes, why not try this "choose your own adventure" version of the game by web comedy troupe Game Station.
It's nice and slow, giving you ample time to consider your choices, then decide on what seems the most logical course of action.
Being a "choose your own adventure" game, logic of course plays no part - it's all cruel chance - we're just letting you know there's time for logic if you feel like sorting it out that way regardless.