Despite its departure from the novel, the film adaptation of World War Z was compelling because of its terrifyingly fast and uncharacteristically cooperative zombies. Seeing hundreds and thousands of undead bodies crawling over one another to create haunting swarms or towering pillars helped make the staple fictional enemy feel fresh, and its the exact energy that gives its loose video game adaptation the same strong foundation. When it's all about gunning down thousands of enemies with a couple of friends, World War Z is at its most entertaining.
Simplicity is at the heart of World War Z. Each of its 11 stages are filled to the brim with undead enemies for you and up to three friends to mow your way through, using an assortment of firearms, special weapons, and explosives. There's not much else to each of these missions that make them more complicated, which works for World War Z in its initial hours. The straightforward nature of gameplay makes it incredibly easy to jump into a match and immediately understand how to contribute. Pointing a gun at enemies and pulling the trigger rewards you with satisfyingly gruesome kills that thin the horde, allowing you to push further to the next objective. Optional lower difficulties for each stage let you get by without much synchronized play, letting you get to grips with World War Z's multiple classes.
Unlike Left 4 Dead, which is clearly an inspiration for the cooperative gameplay, World War Z gives you the flexibility to choose which roles you fulfill in a team. Although you're able to equip any weapon you find, classes determine what you start with and what unique abilities you bring to each match. The Exterminator, for example, excels at lobbing Molotovs into gathering waves of undead enemies and has an upgrade tree that increases damage done to enemies that are on fire. The Medic can heal teammates without a first aid kit, and Gunslinger can distribute ammunition for use across all weapons. Classes can be tweaked slightly with unlockable traits (which you purchase with in-game currency earned from playing matches), though you can only equip a handful at a time.
The classes are fun to experiment with, and as you start taking on harder versions of each stage, they become more crucial to your success. At higher difficulties enemies are more ferocious and deadly, while you have fewer chances to revive downed teammates before they die. Friendly fire also becomes more unforgiving, making the frenetic nature of firefights a lot more challenging to deal with. These combine to better encourage well-balanced team configurations that capitalize on both healing and offensive abilities in order to survive, highlighting the usefulness of each class ability better than lower difficulties.
Playing as your favorite class unlocks perks for said class faster, and the same applies to the weapons you pick up. Kills accumulated with each weapon levels them up, giving you new attachments to purchase that increase damage, handling, reload speeds, and more. Weapons are separated into ascending tiers, with tiers increasing as you progress through a stage. Although you'll start with a Tier 1 pump-action shotgun, for example, you can just as easily find a magazine-loaded and automatic version before the climactic final battle of each story chapter. This gives you a reason to slow down and poke around each of World War Z's maps, as well as hunt down valuable explosives that give you entry into weapon-laden safe rooms. Picking up a new and improved weapon has an immediate and tangible effect on your ability to cut down increasingly large hordes, which makes finding the perfect one rewarding.
Stage-specific objectives are less exciting, though, only serving to push you from one combat encounter to the next without much strategy. Most of them just pad each mission with uninteresting interactions with switches or terminals just to group everyone up again before the next big zombie encounter. They're boring and rarely offer any opportunities for synchronized team play. Only a handful of scenarios attempt to add some variety into the mix, and even fewer succeed. One standout encounter tasked me and my team to venture into a multi-level room filled with toxic gases, forcing us to hunt for keycards that could be used to interact with terminals and bring the gas level down. This one scenario makes you wish there were more like it spread throughout the multiple story chapters, and it's frustrating that it isn't the case.