The premise of the game is simple. You are one of four human survivors and your aim is to survive a zombie apocalypse which has left the vast majority of the population infected with something a lot worse than swine flu. The co-operative gameplay is excellent and you really do have to work together if you want to survive. Communication with your team mates, caution and the determination to protect each other are vital for victory, especially on the higher difficulty levels or in the incredibly tough Realism mode.
There are five campaigns, all fully fleshed out and featuring some dramatic set-piece moments. The level design is superb and although you are progressing down linear corridors in each environment there are frequent route choices and the genuine illusion of a wider world. The most impressive thing about the level design is the intuitive nature of it, much like Half Life 2 given an apparent choice of two routes you’ll find yourself taking the right one immediately most of the time.
The basic gameplay is standard first-person shooter. You can carry two weapons, an explosive and some health boosting items. The first slot is reserved for the big guns and you can find a wide variety including all the FPS staples from sniper rifles to shotguns. Your second slot is a back-up pistol and you can wield dual pistols if you find another one although I’d recommend ditching it in favour of a melee weapon. There are nine melee weapons on offer from katanas to guitars, and you can also get your hands on the holy grail of zombie slaying – the chainsaw. This being a Valve game the crowbar makes an inevitable appearance.
The hordes of infected pouring in through every available opening are bolstered by some new additions to the super mutant line up. Added to the original Hunters, Tanks, Smokers and Boomers you’ll find Spitters, Chargers and Jockeys. Spitters create acid pools which you don’t want to get stuck in, Chargers predictably enough charge at you and pound you into the scenery and Jockeys jump on your back and take control. The mixture of challenges represented by these mutants make the gameplay varied and you need to react differently to each one, although you ultimately just want to shoot them all.
The various campaigns are overseen by an AI director who changes the action every time you play. Pick ups will change, zombie hordes will attack in different places and you’ll face a random array of the special mutants. This lack of predictability or standard scripting makes each play through a fresh experience and really boosts the replay value.