Valve is a rare beast. As a development house they’ve turned out some of the definitive works in the first person genre. Half Life 2, Team Fortress 2, Portal — The Orange Box alone plays out like a who’s who of modern first person gaming. When they announced their latest project would take the form of a zombie apocalypse, we all waited anxiously to see if the Valve hit factory would be able to bat another one out of the park. Would their perfect track record remain unscathed in the face of a zombie invasion? 

Left4Dead places you in the shoes of one of four survivors of a recent zombie apocalypse. Together you and your three squadmates will form a tightknit group and attempt to gun down thousands upon thousands of living dead. The catch? Your squadmates are going to be other gamers, just like yourself. Left4Dead is more than Valve’s attempt to tackle a classic B-movie sub-genre; it’s their attempt to create a co-op game that redefines what a co-op game can be.

Rather than offering co-op as a feature to supplement the single player campaign (as we’ve seen in games like Gears of War or Halo 3), the co-op in Left4Dead is the campaign. With L4D Valve has closed the gap between the single player story experience and the multiplayer social experience by creating a title intended for group play from the get-go. For the first time we’re given a story mode that’s meant to be played through with friends, and it’s a fine fit. Once again Valve has taken a gameplay element that other titles try to incorporate as part of their massive offerings, and refined it to perfection by making it the only offering. They did it for multiplayer team games with Team Fortress 2. They did it for puzzle elements in FPS’s with Portal. And they’ve done it again with Left4Dead.

Built off the Source engine, combat should feel very familiar to anyone who has played Valve’s previous titles. A small selection of weapons and explosives will be at your disposal, and unlike other horror titles you’ll rarely find yourself running low on ammo. Unlike the sluggish Romero zombies that fans of other survival horror titles have gotten used to, Left4Dead’s zombies travel in lightning fast hordes like in 28 Days Later. Sometimes you’ll see hundreds of them come barreling down the street in a pack at your tiny little group, and all you can do is pray. The real tension kicks in when you’re squaring off against a horde like that needing to find the time to reload every 8 seconds or so. It’s real edge of your seat, nail-biting stuff.

While the hordes make up the bulk of the zombies you’ll see in game, a number of special zombies will pop up from time to time. Smokers will wrap you up in their tongues from 40 feet away. Boomers will vomit on you impairing your vision and signaling the horde to your whereabouts. A few others exist, from Hunters to Tanks, and they all offer their own unique twist to the game that can incapacitate you in seconds. Of course, if you get tired of being slaughtered by special zombies, you can always be one.

Versus mode is Left4Dead’s multiplayer game for those with a competitive streak. Two teams of four take alternating turns playing through a campaign as survivors, then zombies. Those looking for a challenge won’t find one better than this. The survivors are playing a game that essentially mirrors the main game co-op experience, except with far more special zombie encounters. Zombies can respawn infinitely until the survivors have been taken out. It’s a nice little change from the main game, and it makes the game a hell of a lot more aggressive.

Multiplayer isn’t just relegated to online, though. Left4Dead offers two player offline split-screen just the way I like it: vertical. I’ve said it before and I’ll say it again, horizontal split-screen is a relic of the SDTV era and it needs to be put to rest. HD gaming doesn’t mean having to say your sorry, especially to those still on SD’s who expect us to play our offline co-op like it’s a panoramic photo. The offline co-op can merge with the online as well, so you and your friend in the living room can still make an online foursome happen.

The campaigns themselves, while distinct in their location and maps, don’t differ much from campaign to campaign. Each of the four campaigns (presented as their own B-movie) feature the same cast of characters battling the same kinds of zombies as they attempt to make their way to a rescue point. The different environments and maps really do help to make for a fresh experience, but it would’ve been nice to see some special zombies being distinct to certain campaigns. Each also ends campaign in a similar clusterfuck, with your pals fighting off one last massive attack as you wait for rescue. The clusterfuck is a little different each time as you need to learn your surroundings if you’re going to survive, and while it’s a ton of fun it would’ve been nice to see the campaigns change thing up a bit.

My only other beef with the game is with the single player options. I know I just finished telling you about how great a co-op experience this is, but let’s not put the cart before the horse. My complaint isn’t with a lack of single player, but with what’s already there. Much as many other games tack on a co-op experience, L4D has tacked on a single player one. Once you start it though? You can’t have friends jump in and join the slaughter. Now here’s where my beef really kicks in: if you chose “Friends Only” from the campaign menu instead of single player, you can still play solo and then your friends can join in whenever they want. You can even switch the setting to “private game” so that your friends can’t join unless you invite them. So why did they feel the need to include a gimped single player, when a full fledged one already exists with a few logical choices from the main menu?? It’s a moot point anyways as playing Left4Dead solo really does lack that certain something. That frantic exhilaration of fighting your way through a hundred undead really isn’t the same when it’s not a shared experience.

Despite my few complaints, Valve has done exactly what they set out to do: Left4Dead sets a new standard for co-op gameplay. By keeping the campaign lengths under 2 hours, any group of friends can fit a full run-through into their schedule. By keeping the mechanics simple and familiar, anyone can jump in and be part of the fun. It’s accessible, edge of your seat zombie massacre fun. Finally, someone has given the survival horror genre the makeover it has so desperately needed, and I couldn’t think of a better developer for it than Valve.

Left4Dead is available for the Xbox 360 and PC now. The Xbox 360 version was played for this review, and currently retails for $59.99. You can purchase the PC version on Steam for $49.99 by following this link.