The dead are back in town, this time it's New Orleans that has taken the brunt of the zombie infection, don't worry though because Valve has given us four new heroes to brave the zombie infestation and a whole host of seriously cool toys to battle these undead with in Left 4 Dead 2.

Story

Coach, Ellis, Nick and Rochelle are thrown together in this zombie apocalypse. There's no real story exposition in lavish cut-scenes or vignettes, Valve have placed their story into the character dialogue and the world itself, if you look closely enough at the walls and the environments you'll see hints as to the events that took place before the Big Z infestation. Over the 5 new campaigns it's about getting the heck out of Dodge without being turned into zombie chow.

Gameplay

Right from the start, there's that much new content here in the game and design that it's unfair to call 2 an expansion. This often feels like the game that Valve should have released in the first instance, yet without Left4Dead there would be no 2 and its many innovations in terms of gameplay and the highly effective AI-Director 2.0. I cannot stress just how much fun 2 is in terms of pure adrenaline soaked cooperative gameplay.

For those of you new to L4D well, go and play the first game right now...we'll wait...not long though. Ok, moving on.

2 brings a lot of innovations to the standard FPS gameplay of the first game, new to the sequel are 3 new infected subtypes, retooled standard infected and rebalanced/redesigned special infected including the Witch who no longer sits there and just cries, she can actually patrol now and she is a lethal force to be reckoned with. Additionally Valve have changed up the just-shoot it gameplay by adding melee weapons, a plethora of those run the gamut from the old-skool Freeman favourite, the crowbar to the more eclectic samurai sword, and the downright awesome frying pan, the noise alone was worth the wait, the star of the show is the chainsaw that allows you to relive moments from Army of Darkness.

There are three new special infected to change up the infected gameplay and they provide a cohesive cooperative challenge. The Spitter can throw a gob of noxious area-effect goo that inflicts heavy damage to anything in the area of effect. The Charger is a vicious melee combatant that comes out of nowhere at high speed, can snag a survivor and pummel them into the ground before the rest of the group can react to save them. The Jockey is a truly evil infected that can take control of a survivor and lead them off, usually into a puddle of Spitter goo or even other infected. It's not uncommon to see the Spitter lay down a goo patch and have a Charger ram a survivor into it, whilst a Jockey comes along to ride another towards a massive group of infected or a Tank.

There are also new weapons to counter the infected with, a vast array of guns and additional components such as laser sights. There are also new ammo packs, you pick them up and then deploy them allowing the whole team to stock up on fire bullets and so on. There's even a way to bring back dead survivors as long as you have the defibrillator equipped in your inventory. Molotov cocktails make a welcome return along with pipe bombs and the newly added, boomer bile, contact goo that makes the zombies attack anything it touches. An Adrenaline shot can give you a much needed health boost and it also speeds up your reactions allowing you to avoid zombie attacks and so on, for a small amount of time.

Valve have also added newly expanded level design, daylight environments and they have made sure that balance changes from L4D found their way into 2. There are various game modes and a new Realism Mode that makes things even harder by removing the visual cues like lines around survivors so you can't see them through walls etc. It also ups the ante on the infected making even the normal infected extremely hard to put down, for those people who complained that L4D was too easy even on Expert.

Survival Mode returns from L4D and there are now 5 campaigns to plow through, some of these are much longer than others and they all have a pretty interesting finale.

Crescendo events are back, but tweaked so that you actually have to do something like turn off an alarm before you're overwhelmed by hordes of undead. These are often not static defence sub-events either; they can be quite long, especially in Dark Carnival. Finale events are much improved and they offer a greater challenge since you're often given a particular mission to accomplish, gas up a car so that you can make your escape for instance. This means you'll be collecting gas cans to fuel the vehicle up as increasingly harder waves of infected come-a-callin'.

With the upgraded special infected, new weapons, new items and new events, the gameplay stays true to the original but offers a greater and diverse degree of tactics, especially with the addition of melee. The AI Director 2.0 controls so much more now, not just zombie placement and mob events, it controls lighting, atmosphere, effects, music and more. In many areas it can create a random path through something like a graveyard ensuring that you're never going to play the same kind of map route twice.

You can go it solo with 3 AI buddies, system link it up, play split-screen with a friend or jump onto Xbox-Live for some serious cooperative or adversarial fun.

Graphics

With the daylight environments, L4D2 looks pretty decent, it doesn't seem to have the wow-factor of other titles but then again you don't actually spend all the time looking at the graphics, you're too busy trying to survive against waves of lethal enemies from all directions in this sequel. The use of various spot effects and graphical tricks such as different filters and so on creates the most visceral zombie apocalypse this side of a George.A.Romero movie. L4D2 manages to create a chilling atmosphere of a zombie outbreak using an engine that's showing a little age now, proving really just how good the Source Engine is in the hands of the developers.

The level of detail on the survivors and the infected is still rather good and it looks nice enough.

Animations

A few times the animation fails to synch up properly, notably when healing other players and so on, but it can be forgiven. The rest of the animations are good quality with a high level of motion detail paid to the various infected, the survivors and the special infected. The quality of the infected death animations when shot or when struck by a melee weapon is great, you will actually see some of them poke at the big hole a shotgun or high powered rifle leaves in their gut before falling over.

The level of gore isn't really anything to be concerned about, I mean its zombies. We see far worse in news reports.

Physics

Source has always had good solid physics and in the case of L4D2 it has been tuned again, explosions are suitably impressive and the environment feels more reactive now, especially in the first campaign when you're inside a building that's on fire and collapsing. You can feel each crash and shake as the roof comes in above you. Melee physics has a nice feel to it as well, the frying pan makes a beautiful defensive and offensive weapon smacking zombies to the ground.

AI

The survivor AI is pretty solid for the most part, though sometimes it will go and do something completely idiotic, rather like a human player. I've not seen too many bad path-finding moments in the sequel though compared to L4D. The infected AI is good, it runs the gamut from blindingly stupid zombie AI to cold and calculating Hunter AI and the teamwork between several core infected sub-types can be quite scary to see in action. Being dragged off by a Jockey into the arms of a Smoker or a Hunter for instance whilst the Spitter coats you in acidic goo, can be most unfair. It is also pretty awesome too.

Sound

Valve have done a good job here on the audio, it's extremely atmospheric and the use of key audio signatures for the various infected can provide a valuable clue as to what kind of bad guy is about to rip your head off. Or try to eat your brains. Weapon sound-effects are great as well as the sound of the frying pan as it dongs off the face of a zombie, it's comparable to the awesome moment in Psycho where Norman Bates first hits someone with a shovel.

Music

There's a variety in the music of L4D2 that isn't present in other games, suffice it to say that the music is excellent and the strings for When the Saints Come Marching in totally nail the 'shiver down the spine' factor. It's utterly superb stuff and extremely chilling.

Voice/Dialogue

The voice artists do a great job with their lines and whilst the new characters lack the appeal of the old 4, you can find yourself warming up to the various characters over time thanks to their performances. The dialogue itself is very well written and fills in various background details as time passes.

Multiplayer

Adversarial is back, tweaked and better than ever with the new infected and Valve's patient balancing. It's a literal blast to play as the new types and fans of the original will find a heck of a lot to love here. You can play with friends over system-link, or rock out online and join the carnage. Not content with the original adversarial, Valve have made the game even more frenetic by adding Scavenge to the mp game type. This is a special mode where you must collect gas cans to fuel up a generator before the 2 minute timer expires. Each can add 20 seconds.

Your enemies, 4 special infected, will do their level best to stop you. The best two out of three matches wins, at half-time the players switch sides.

The main crux of the matter is that Valve have taken multiplayer and tweaked it from L4D, they've made sure the new maps and modes work well with the new survivors, new weapons and items as well as the new special infected, basically, it's pretty much the best adversarial fun you can have in a zombie apocalypse yet.

The bottom line

Left 4 Dead 2 isn't Left 4 Dead 1.5 since there's a wealth of new content, new features, tweaked A.I. Director 2.0 and more changes than you can shake a stick at. I have a feeling if this game came out last year, people would have been really happy with L4D but without the former you can't enjoy the latter, just the same as with Assassin's Creed. If you loved L4D and you are boycotting L4D2 then you are missing out on some great follow-up action, 2 is the sequel that we hoped it would be and more.