Zombie apocalypse is a term that's been thrown about an awful lot in the last few decades of cinema and videogaming. The fact that it's such an enduringly popular sub-genre is testament not to the wealth of imaginative ideas that it holds - when you scrape away the rotting flesh and get down to the bare bones of it, no zombie story is that much different from any other - nor to the suggested symbolism concerning mob-mentality or human depravity, but rather to the fact that - no matter whether it's the dead coming to life or a bio-engineered virus - zombie invasions are cool. I don't mind if the undead in question shamble or sprint, lunge or leap, groan or growl - I just like the fact that the central theme of every single zombie movie, game and book is survival; the few against the many, the endurance of the human spirit. That and the fact that bursting heads like pumpkins never gets old.

Since the original Resident Evil placed gamers in the shoes of the plucky-yet-unlucky S.T.A.R.S. team and made them shit bricks every five to ten seconds, the gaming community in general has had a special place in its gestalt, overly-critical, caffeine-powered heart for games that drop them in at the deep end with limited ammo, sparse first aid kits and a tiny inventory, then force them to fight to the bitter end. It's a wonderful genre to watch on the big screen, but in a videogame - when it's done right - it's pure adrenalin heaven. And Left 4 Dead, the new team-based shooter from FPS geniuses Valve Software, is the perfect example.

Such is the legacy of a developer like Valve that every time they crank up their PR system and announce that a new game is on the cards, the community takes notice. The Half-Life saga is one of the greatest sci-fi stories ever told in videogame form, one that not only showcases what Valve are capable of on a technical level, but also demonstrates that in terms of gameplay they mean serious business. Whether or not Left 4 Dead will spawn a franchise, or even a sequel at all, remains to be seen - but one thing that is certain is that Valve have done themselves proud yet again.

In contrast to Half-Life, L4D is not built around a deep or engaging story. The premise, like many zombie-based releases, is very simple. An unspecified virus (possibly some mutated strain of rabies) has swept through an unnamed American city (and perhaps the whole country, or even the entire world), reducing everyone it has infected into mindless, rage-driven, killing machines. The result is an almost apocalyptic game world that's filled with the maddened infected, eerie, abandoned roads, disturbingly quiet city streets and blood-spattered, shadow-haunted alleys. Through this living nightmare come four survivors who for some reason are immune to the virus, struggling to reach the evacuation point before they are overwhelmed by the ravenous undead.

In no particular order you've got rough-around-the-edges biker Francis, Vietnam-vet Bill, clean-cut IT consultant Louis and student and horror-movie enthusiast Zoey. You can choose to play as any of these characters and they all have identical abilities, so the decision really comes down to a matter of aesthetic preference. It should be said, however, that although you get very little backstory on any of them (all the information there is can be found in the manual), they have very well developed and unique (if slightly clichéd) personalities, chipping in with quips, one-liners, advice and musings on your current predicament. There are many moments throughout the game where an utterance makes you grin, smirk or laugh-out-loud, and this is a clever mechanic that adds a genuine sense of camaraderie to even the single player experience - in short, it makes you want to keep your companions alive, and not least because, if they die, your own chance of survival drops considerably.

The game is split into four standalone campaigns, each divided into five chapters. The objective of the first four in each campaign is to make it to the safe house, a barricaded room that's filled with ammo, first aid kits and guns. Each safe house brings you closer to your ultimate goal - the finale - where you make a last stand against the infected horde until rescue arrives. These rooms are also unique in the game for the graffiti scrawled upon their walls; the frantic, frightened meanderings of other survivors that contain messages to loved ones, conspiracy theories and zombie kill counts, amongst other things, and serve as the only real source of exposition in the game.

You can choose which chapters of which campaign you want to play from the off, without having to complete any of them beforehand. Initially such freedom feels strange in a world where games are usually praised for their storylines and mission longevity, but you will quickly realise that this is because Valve want you to experience the game in your own way. Each campaign plays out like a movie and usually takes one to two hours to complete on the normal difficulty setting. Ramp the difficulty up however and you're in for a serious challenge; alongside the infected horde themselves (of which there are literally thousands) there are five "boss" zombies that appear from time to time, thanks to the much-touted AI Director, which include the Boomer, a slobbering oaf whose vomit (which he sprays at you at every opportunity) attracts the rest of the horde, and the Tank, which is pretty much a zombified Incredible Hulk. Of them all though, the Witch is the one that you really don't want to upset. You usually find her weeping in a corner, and believe me when I say that it's in your best interests to turn off your flashlights and give her a wide berth. All five are wonderfully disturbing additions to the decomposed cast and the fact that they can crop up literally anywhere, at any time, adds a level of tension not experienced since Resident Evil 3's Nemesis stalked you through the streets of Raccoon City for the first time.

The AI Director is one of the best innovations ever to grace a first person shooter. Basically, the game assesses your progress as you play, occasionally being lenient and chucking you a free first aid kit or stash of ammo but usually dropping a horde of infected or a random boss zombie upon you without any warning. If you get to a nice quiet area with full health and a gun full of bullets then the Director will surely punish you for it. This makes every playthrough that little bit different, and while you can learn the layout of a map, it's next to impossible to successfully second-guess the Director. The amount of times you run out of ammo and have to fall back on your pistols (which never run out) because you expected an ammo stash to be around the next corner is surprising.

Your three AI companions are competent enough standing beside you, to the point where they always try to save you from a gruesome death (if it's possible for them to reach you), always go for the boss infected first, shout out when they find ammo or first aid and heal you without a prompt. They're not so hot on tactics, however, and don't use explosives or mounted guns; during a solo campaign they are like a safety net, making you feel that little bit more comfortable in the nerve-jangling environments. If you want to make the most of L4D and really open the game up then sign onto Xbox Live, give your buddies a shout and experience the game that Valve really wants you to experience: cooperative multiplayer.

There is no other game out there that puts so much emphasis on teamwork in multiplayer and, as a result, there is no game out there that offers quite the same experience as Left 4 Dead. Being able to co-ordinate a defence or attack with living, breathing, free-thinking players elevates the game from being merely great to downright fantastic. On a split screen play-through it's fun, but take it online and it's a whole new ballgame; not only can you play each campaign with three others at your side, but Versus Mode lets your party take control of the infected instead, making for some adrenalin-fuelled, head-to-head action as one team tries to make it through the map alive and the other team unleashes everything that the infected horde has at their disposal. You can always see where your team-mates are by the coloured outline that's imposed upon them when they're behind a wall, so it's easy to co-ordinate, and the whole thing is wonderfully balanced and incredibly tactical. When playing as the horde however, the game changes completely, as you can choose to take on the role of one of the boss infected and coordinate spawn points for the zombie masses. Apart from anything else, playing the bad guy is almost always more fun!

The Source Engine handles the number of enemies onscreen very well, with no visible slowdown or annoying pop-up enemies or obstacles. The player models are awesome and the detail in their facial expressions adds to the emotional tension; just watch the fear in their faces when their health gets low. The whole game has a very bleak, grey kind of sheen to it, but this only serves to heighten the atmosphere and within a few minutes of playing, you won't notice that a lot of the zombies are identikit. The environments are perfectly rendered and incredibly detailed, with ransacked office blocks, abandoned tenements, grimy sewers and dark, foreboding woods all making an appearance. Adding to the ambience even more is the sound; play this game with the lights down and the volume up and you'll literally feel the tension it creates. One moment you're creeping through an abandoned airport departure lounge, the next you hear the rumble of stampeding feet, a distant roar, and then the music kicks in as fifty-or-so zombies come crashing towards you, with a Tank bellowing in their midst. Then, just as quickly, the silence returns, punctuated here and there by some perfectly-acted wisecrack from Francis. Epic.

With a stack of impressive achievements - some of which can only be unlocked when playing as the infected - and so much variety in terms of enemies and surprises, Left 4 Dead is only really let down by a lack of content. Many will find the assortment of weapons (two types of shotgun, an uzi, an assault rifle and a hunting rifle) meagre, and with only four scenarios to play through, the single player aspect can become very samey, very quickly. It's a wonder that Valve didn't add in a couple more maps and a few more toys to the arsenal, especially given the size of some of their previous titles. But then, this game really was designed with co-operative play as its primary focus, and Valve have promised a lot of downloadable content over the coming months, so perhaps they'll be adding some nice bundles to keep the fans happy. By the time this review gets out, the PC version will already have a handful of player-made mods available that the 360 community will miss out on, though how this effects the popularity of the game on either platform naturally still remains to be seen. Though a hard game to score because of its dual nature, Left 4 Dead is still a standout title. The single player is short and lacking in content, but not enough to really harm the experience since what you've got is so incredibly playable and well-crafted. Besides which, it was designed as a multiplayer game and in that respect it outstrips just about every other shooter on the market.

Fun, frantic, fresh, innovative, stylish and addictive, Left 4 Dead is a game that you will enjoy when playing alone and fall in love with when playing with friends. It's what survival horror is all about: teamwork, desperation and endurance - and in terms of crafting an atmospheric, pulse-racing FPS experience, Valve have absolutely outdone even themselves. This game proves, without a doubt, that the Zombie Apocalypse sub-genre ain't dead yet... pun very much intended.

Reviewed by Mick Fraser for AceGamez (All Rights Reserved).