Horror, Satire, Mockumentary
Horror
An army of your friends and relatives have risen from their bloody graves and are chomping at your ankles as you run, desperately try to find a safe place to sleep. What emotion do you think this scenario is trying to convey? Romantic love? Um, no. Swashbuckling adventure? It sounds a little more dire than that. Horror? Ding!
Teen love stories have all but been defanged the vampires, werewolves can earn our sympathy, and creatures from the Black Lagoon are no threat if you just read the "Do Not Swim" signs surrounding the Black Lagoon. But zombies are plain scary, even in comedies.
There's no reasoning, no falling in love, and no avoiding zombies. Like an apocalypse on two legs, they'll find you unless you find them first. And even if you survive your personal encounter, the cost of human life might cripple law enforcement, the government, and perhaps society as a whole, leaving you to wander a hell made from the shambles of your former life.
Sounds pretty horrific to us.
Satire
Horror and satire? Seriously? Well…yes and no.
World War Z shares several qualities with satire. The laugh-out-loud, comedy quality is missing in action, mostly thanks to a healthy dollop of run-for-your-life terror. But, the part of satire that uses absurdities to criticize aspects of society, now that is definitely present.
The absurd elements are—what else?—the zombies. They are a supernatural element, and as much as we love them, the idea of corpses reanimating simply to go nom on our gizzards is pretty darn silly. By using this silly element, World War Z manages to criticize so much of our modern existence: modern man's lack of survival skills, bureaucratic inadequacies, racism, nationalism, first-world problems, and human rights violations.
While maybe not technically satire, World War Z has a little bit of silly that can be taken with a whole lot of seriousness.
War Drama
Brooks's novel is based a lot on Stud Terkel's The Good War—a nonfiction book consisting of interviews from World War II survivors (source). As such, World War Z is very much a war drama but with a unique twist—and no, we don't mean just because it plays host to a cavalcade of cannibals.
Terkel's book focuses on World War II, a very real war that took place in our very real reality. But the zombie wars are completely fictional. This allows Brooks to borrow different parts from all sorts of historical wars. In fact, the war historians among us will notice Brooks drawing much imaginative inspiration from World War II (obviously), the Cold War, the Vietnam War, the Iraq War, World War I, and even the Revolutionary War.
With so many different wars present, World War Z becomes less a war drama focusing on the effects and consequences of a single conflict in human history, but on the entire idea of war and its relationship to human society.
But with zombies.