So even months away from its release, I may as well declare what some already know: Left 4 Dead is going to be a major fucking hit.

The developers have nailed this thing in every way possible. The pacing. The polish. The guns. The zombies. Even the console port is great.

One thing Valve found out early on is that the media--and by that I mean screenshots, video, and the written word--does not do this game justice. It's a bit like watching a space shuttle launch on television, or listening to someone read a comic strip out loud. It's missing necessary elements that make up the equation.

Watching a video of Left 4 Dead, you don't really get a feel for how dangerous walking around a corner can be. You don't have a sense of the tense tactical choices going on, or the devious nature of the artificial intelligence. You don't know the fun of tossing a molotov cocktail into a group of zombies while laughing about it with your co-op cohorts.

But it's all in there, and it all adds up to a wholly original cooperative experience.

Tag, You're Dead
Some of my fondest childhood memories are of playing hide-and-go-seek tag in the dark. The kids on our block played religiously. We would wait until nightfall, then scramble for the bushes, squatting in a state of pure nervous anticipation, prepared to make a run for it at any moment.

Left 4 Dead is the first multiplayer game I've played that nails that same sense of tension and release in a randomized scenario. When a boss Infected blasts through a wall, I'm back in my backyard, running for my life--only this time armed with shotguns and assault rifles.

The game will ship with two modes: Co-op and Versus. Co-op challenges players to survive the Infected AI on their way through lengthy scenarios. Versus does the same, but adds an additional four players in the role of the Infected, trying to stop the humans from reaching checkpoints. At the end of a round, the teams switch sides, attempting to beat eachother's times.

In either mode, the goal is the same from the human perspective--escape with your life.

The importance of the game's Director AI can not be overstated. This is the system that gauges the condition of the players and intelligently generates climactic battles, guaranteeing a perfect rollercoaster ride every level.

More importantly, it also randomly places zombies throughout each scenario, ensuring that you never find them in the same place twice. This leaves you and your friends totally in the dark, helpless to predict whether a massive horde of zombies lurks around the corner.

Even with all of this enemy variance, the game would still be in danger of becoming repetitive if not for its solid level design. Office buildings, hospitals, sewers, rooftops--Valve is always mixing up the terrain, changing the tactical situation to allow for surprising ambushes and interesting shooting scenarios.

If replayability is key to the longevity of multiplayer games, then Left 4 Dead could easily become the next online standby, carving out a nice co-op niche between Team Fortress 2 and Counter-Strike.

Decisions, Decisions
When a zombie horde rushes around a corner, what do you do? Stand back and let your team take the brunt of it? Coordinate and attempt to call out firing zones?

When your teammate is wounded, do you give him your medpack, or keep it for yourself? When a horde of zombies is overwhelming your position, do you risk tossing a molotov into the middle of your squad?

Left 4 Dead is constantly challenging you to make these choices, and usually in the middle of a ridiculously chaotic battle.

"Co-op: it's laughing and having a good time, punctuated with profanity," Valve's Chet Faliszek told me. He's right, but it's not exactly what you'd expect.

In most games, you laugh when you're doing well, and swear when the game beats you. In Left 4 Dead, you laugh at the absurdity of the situation, and you curse when you fuck it all up and get your team killed.

Without a cohesive squad, working your way through the game's movie-sized scenarios quickly becomes impossible. As in the best horror movies, stragglers are always picked off immediately.

You have to stick together to stay alive, and it's that naturally-evolving group dynamic that really makes the game something special.

Dead on Arrival
Fall is shaping up to be a great season for co-op gaming. LittleBigPlanet is looking fantastic. Fable II should be a good time.

But for a shooter fan, nothing is as exciting as Left 4 Dead. With the unpredictable scenarios running the ideal length of two hours, the threat of co-op addiction is as scary as the game itself. And now those with slower computers have no excuse to miss out: the Xbox 360 port is a fine piece of work, and a perfectly viable alternative.

No matter your chosen platform, November 18 is not long off. So watch a video, I guess. Look at a screenshot. Imagine the potential, and know that Valve has reached it.