It is every man's nightmare: The dead have awoken, crawled out of their graves and ruined your favorite game.
The easy questions (How did they get here? How do I work this? Is that my beautiful wife?) are irrelevant - the undead are here, and they must be dealt with swiftly. Thankfully, you are not alone. A squad of up to 14 of your brothers in arms walks beside you, and you are all armed to the teeth. A shotgun may not be the best tool for the job, but it's what you've got, and one or two shots to the head will usually bring down anything - even a zombie. It's a good thing, too, because one or two shots is all you're going to get.
Forget what you've seen on TV. These zombies are fast. Really fast. And they've got swords. They can sweep in over your barricades, "lock on" to one human target at a time, and wipe out an entire squad before you even know they're there. And that's just the beginning: These zombies don't just kill their human foes, they infect them with their insidious ailment, zombifying them instantly. Your fellow warriors - men who had once stood bravely by your side, repelling the undead swarm and telling dirty jokes about your mother - can turn to foes in a heartbeat. You like to think this keeps you on your toes, but in truth it terrifies you; mainly because you could be the next to go.
The beginning is always the same: A lone zombie appears on the horizon, hungry, mean and ready to ruin your day. It takes him a minute to get his bearings, but after that he's all about the killing. You can use that precious moment to your advantage by finding a place to hide and barricading yourself in, or you can stand out in the open, gun at the ready, hoping you'll spot him before he spots you. You've seen what happens to the guys who choose the second tactic. They usually realize their mistake just before it's too late, and then there are two zombies. That way isn't for you. You're smarter than that - this time. Instead, you book it to join the rest of the squad in Room 4, where they're already hard at work erecting a barricade. Having seen the zombies in action, you're not as confident as they are about its effectiveness, but you lend a hand anyway. It's all you can do.
The zombies hit the barricade before your line is fully formed, but a handful of shotgun blasts take them down pretty quickly. You start to feel confident, like you might actually make it out alive this time.
The first few times the zombies hit the wall. They're careless, charging headlong into a solid wall of buckshot. After a while, though, you realize that they've been testing you - searching for your blind spot. "Cover the left hallway!" you start to shout, but it's too late. A zombie has locked on to one of your squad mates who was looking right when he should have been looking left. It's a mistake he'll never make again. You can't tell who it was, but now he's one of them.