While World War Z is based on the movie, not the book, it still takes some inspiration from its literary source material. It follows 12 different characters in three stories set in three locations: an infected Jerusalem, New York City and Russia. Each of the three chapters will be broken up into three levels and tell the story of various survivors attempting to overcome the undead hordes that threaten the safety of the world.

The most obvious starting point for discussing World War Z is, of course, Left 4 Dead. The two games share a lot of the same DNA — and not just because they're four-person zombie shooters. The general game design is quite similar. You're given control over four survivors and have to take them through a semi-randomized environment until you reach the ending, punctuated by occasional dramatic moments that put you up against dangerous odds.

There are even special zombies that are more dangerous than the usual. At the moment, there are four: the Bull, who is heavily armored and hard to kill; the Creeper, who doesn't appear on the map and ambushes you; the Hazmat Zombie, who explodes and releases toxic gas; and the Screamer, who attracts zombies to him. These foes can throw a nasty wrinkle into the mix, but it's satisfying to figure out how to defeat them.

One thing that sets apart World War Z from Left 4 Dead is how the zombies function. They're zombies, but true to the film, they're a rushing wave rather than individual zombies. This means that they're more dangerous in hordes — and not just due to sheer numbers. Once a horde of zombies is alerted, their overwhelming presence allows them to do things they couldn't alone. We saw an example of this in the demo. A swarm, once woken up, began to form an inhuman pyramid that allowed them to scale a previously unscalable wall and swarm us. We could use grenades and firepower to damage the pyramid and slow the advance of the awful wave of undead flesh. Failure to do so would mean they'd overwhelm us. It was an interesting challenge because it really played into the idea that these zombies were dangerous in numbers.

Also different from Left 4 Dead is that World War Z has a specialization system. Independent of the playable character, you'll choose a class with abilities that level up as you play. These can range from increased melee capabilities to modifying weapons (such as making a Masking Grenade that can disguise you as a zombie target) and other nice little perks. They don't change the entire game, but they provide a small boost. There's also weapon customization that functions under similar rules. Any weapon you find in the game can be customized to match your weapons.

All in all, World War Z is shaping up to be a fun entry into the cooperative zombie shooting genre. There are enough fresh ideas and style to be fun to play on its own merits, and the Left 4 Dead formula is tried and proven. There's a lot to like in the brief demo we saw, and we're told the game is designed around replayability. It should be a boatload of fun to play for fans of zombies, co-op titles, or fans of both. World War Z is coming to the PC, PS4 and Xbox One in 2019.