I swing over the side of the boat, cutting a path to Francis just in time to help him back to his feet. They swarm me almost instantly, pummeling me from all sides, providing just enough of an opening to let me think I might make it back to the ship before knocking me down. I’m screaming for help while emptying my pistols in to them, but I already know no one is coming. Out of the corner of my eye, I can just make out the outline of Francis being drug down again. The pistols empty, my health bar slips from green to yellow to red, and the screen starts to dim around the edges…

Left 4 Dead is more than the zombie game I’ve always wanted without realizing it, it’s also pretty much the only online multiplayer experience I’ve had the patience for since Team Fortress 2 arrived a year and change ago. That both are from Valve is hardly coincidence – indeed, it’s hard to imagine the former existing without the lessons of enforcing cooperation between players first taught by the latter. But where TF2 introduced players to the ida that a team of average players working together would almost always overcome a team of more skilled lone gunman types, L4D tightens things even further by sticking hard and fast to the core rule of all zombie fiction: if you don’t work together, you will die alone. For better or worse, the three survivors accompanying you from safehouse to safe house, whether they’re human or AI bots (and, as a quick hat-tip to the lovely computer brain running things behind the scenes, I should mention that I was the only actual person in the above anecdote), are your best and only chance at making it out alive, and vice-versa. The fear of death as a motivation for sticking together is somewhat balanced out by the game constantly congratulating players on saving their friends by watching their back, healing them up, or even rescuing them from a Hunter or Smoker, but it’s never really goes away. Even in a safehouse, surrounded by friends and a pile of unlimited ammo, you can never quite shake the feeling that the walls could come down at any moment.

The results of being asked to trust the computer, complete strangers, or (sometimes worst of all) your friends with your livelihood are almost always unpredictable, and never fail to entertain no matter how many pieces you end up in. As great as it is to power through with a team of Captain Sensibles ready and will to shoot massive holes through anything that moves, it can be every bit as fun to go in with three little lost lambs who’ll snap the first time they hear a Witch sobbing in the dark. Sure, it can annoy to have your team fall to pieces within sight of a safehouse or while waiting for rescue, but it also offers a touch of realism that only you and your fellow players could have brought to the game. For all the atmosphere created by Valve’s carefully smashed levels and occasional pre-scripted flourishes, for all the looming menace that the AI Director adds by knowing just the worst possible moment to spawn of a wave of undead right behind you, it would all be for naught without the very real panic provided by the players. It’s a zombie film does as a conversation rather than a lecture, and there’s really nothing else like it.

Left 4 Dead is already one of my favorite games so far, and there’s so much I haven’t done in it. I haven’t even touched the “Blood Harvest” campaign, set in a rural farmland with little in the way of shelter and lots of wide open spaces for enemies to come at you from. I haven’t tried the Versus mode, where you take on the role of one of the Special Infected and use your knowledge of the maps to torment the other side. I haven’t seen all the hilarious scrawled messages between other survivors long since gone that line the walls of the safe houses. I haven’t managed to take down one of the monstrous Witches with a headshot, something I keep trying despite it ending in a mess of tears and blood nearly every time. I haven’t seen anything as funny as the time at the end of “No Mercy”, when my valiant stand off against a Tank was cut short by him punching me so hard I flew off the hospital roof like a rocket. For a game some have criticized as skimping on content, Left 4 Dead seems to bristle with new opportunities for amazing, completely unpredictable moments. It’s a game that I come away from each time with a new favorite bit, and while I’m sure that’ll wear off eventually given time, it’s not something I see happening any time soon.