5. Left 4 Dead
Just from the title of this game, you can tell its not going to be a world filled with sunshine and lollipops. The Left 4 Dead universe is in the midst of a zombie uprising. Most people have been turned into blood-thirsty zombies (and the fast kind, too), mindlessly chasing after flesh to feast on. But a select few have been turned into something far more terrifying; mutated zombies. If you thought being a zombie as bad, what if you became a Boomer; an obese zombie that endlessly vomits over everything and can be exploded by a single heavy impact? Even worse, what if you were eaten by one of them? Imagine the horror of being a normal guy, without the handguns with infinite ammunition, being caught by the tongue of a Smoker, then strung up and torn apart by the claws of a Witch. But if youre one of the "lucky" few who, like the four protagonists, havent been infected, chances are you are immune to the virus, or in other words; a carrier. Being a carrier is just as bad, as you will either have to endure being tested and experimented on by scientists desperate to find a cure for the virus, or you will be killed by other survivors who arent immune because theres a strong possibility you will infect them with it.