Computer-controlled survivors do an acceptable job of pulling Hunters off and blasting Boomers from a distance, but they can be equally stubborn and infuriating. There are times when the best course of action is to run with your guns blazing, which is a tactic lost on the A.I. When you are ten meters from the open door of a safe house and a Tank comes barreling from behind, there is no logical reason to stand and fight. Nor does it make sense for my teammate to use her only med-kit on me when I am at 50-percent health and she is living solely on the temporary boost of Pain Pills. You can play L4D as a single-player, offline game, but you really are missing out.

One of my favorite features is the ability to play any of the 20 chapters, spread over four campaigns at any time. The experience can feel disjointed, but you never have to worry about which friend beat which chapter or bring anyone up to speed. You might find yourself running through a hospital in one session, the forests of Riverside in the next, and then back to the hospital, but the repetition rarely matters due to subtly branching paths and random spawns of enemies and equipment. You never know what’s waiting down the street or which way the horde is going to force you through. Still, the campaigns can be beaten in just under an hour on Normal difficulty, and that’s moving at a moderate pace. If L4D is to have any staying power, Valve will need to pump out new maps on a regular basis.

As intensely enjoyable as co-op is, Versus Mode is where the real action is. It plays like any other campaign, with one major twist – four more players get to stalk the survivors as the specialized zombies. The two teams switch back-and-forth as they move through the chapters to see which team can get the furthest, the quickest, and with the most health. Teamwork is actually more critical when playing as a zombie, because of your rotting body, but you do get the benefit of infinite respawns. I only wish that players could choose which type of zombie to be, but I suppose everyone would want to be the Tank.

The online-focus and lack of plot are sure to rub some people the wrong way, but FPS-fans and zombie aficionados have never played anything quite like Left 4 Dead. It is a near-perfect mixture of decayed ambiance and relentless pacing that pushes the boundaries of sanity to the breaking point, and serves as a constant reminder that even the most dire situations can always get worse. While I am still hoping for slow zombies in the real apocalypse, at least I now know who my true friends are, and who is going to run off with the med-kits like a cowardly turncoat.

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