I love zombies more than a grown man should. And shooters…well, I probably play more in a year than most people will over the course of their existence. And the developers at Valve? These are the brilliant guys behind the iconic Half-Life games that have stolen away whole weeks of my life.

Hence, the studio's undead-infested and gun-laden Left 4 Dead series ought to be a recipe for pure, unadulterated awesomeness.

And yet I haven't been able to really penetrate either game in the franchise.

Left 4 Dead 2 (available for PC and Xbox 360) comes a mere year after the original, a fact that stirred up a bit of controversy among the franchise's core fans who thought a sequel so soon would mean Valve was going to abandon the first game and not continue to support its community.

But that's not my issue . I think Valve has proven that it's still dedicated to people who continue to play the original via the recent release of fresh content and modes. Plus, the new game has more than enough distinct features to warrant its release as a standalone sequel.

In fact, I recently chatted with Erik Johnson, the game's senior project manager, and he explained to me how his team reworked the sequel from the ground up as a result of discovering that most people play Left 4 Dead in groups of friends rather than in groups of random strangers, as they originally suspected would be the case.

Consequently, they've added new enemies, like the spitter, a creature that coats wide swaths of ground with noxious bile forcing players to split up, and the jockey, who can jump on the back of a survivor and "ride" him or her away from the party. These enemies' primary function is to split up groups of survivors who work well together, forcing them to communicate even more effectively than they needed to in the first game.

Also affecting strategy is a new collection of melee weapons, ranging from chainsaws and guitars to fire axes and katanas. Melee combat completely changes the tactics players can employ as they fight off the undead. It makes sense for one or two party members to be handy with a crowbar, but if all four prefer close range weapons the group will be at a disadvantage when more powerful infected come charging in from a distance.

There are new modes, as well, including a four-on-four scenario called Scavenge that has a quartet of survivors trying to find gas canisters to keep power generators running while teams of infected try to stop them. And veterans can ramp up the difficulty with Realism mode, which dispenses with many of the game's helpful features, such as the ability for survivors to see each other's silhouettes through foliage and building walls.

And then there are the five new campaigns. Set in Georgia and Louisiana, these missions are composed of four or five stages each and tell the story of a group of four new survivors who are making their way through undead-infested urban and wilderness settings. One is set in a bayou, another during a massive rainstorm in a small town and surrounding area. My two favourites find our heroes in a mall (a la Dawn of the Dead 2) and a semi-deserted carnival-always a creepy setting, regardless of whether its inhabitants are living or deceased.

So, clearly, Left 4 Dead 2 isn't just a quick cash-in on its predecessor's success. Valve saw lots of ways to improve the original's core play and they set about doing just that.

But they didn't address my primary concerns, which revolve around the fact that this game, like its precursor, is designed to be a lengthy, co-operative multiplayer experience.

I can rarely find the sort of uninterrupted time necessary to devote to this kind of game. When you start to play Left 4 Dead 2 you must go in with the intention to play without break from the campaign's start through to its finish-typically an hour or so. There is no pausing. If you need to stop to answer the phone, help your wife, or tend to your kids, the battle simply wages on and you let your teammates down. (Finding the don't-bother-me time required to play through all of the campaigns and modes in this game over the last week nearly caused a rift in my marriage.)

What's more, the stories of these games simply don't satisfy. Valve did their best to make the five new campaigns tell a cohesive story and give the sequel's survivors a bit of personality (Ellis, an affable redneck prone to recollecting useless things at inopportune times, is the most interesting of the bunch), but Left 4 Dead 2 is all action, all the time, and it's difficult to construct a narrative when there aren't any scenes in which characters can just talk to one another and flesh out their histories and a few plot details.

To be completely fair, these are issues over which Valve has little control. They've developed some great action and fun play mechanics, and then chose to put them in a co-operative online game in order to create a specific kind of experience. The issues I lament are the unavoidable consequences of that decision.

To be sure, there are plenty of players out there who care little for compelling game narratives and have all the time in the world to devote to uninterrupted online play. Sadly, I'm not one of them. Left 4 Dead 2 is a good game. It's just not meant for a guy like me.

Left 4 Dead 2

Developer: Valve

Publisher: Valve

ESRB rating: M

Score: 3/4

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