Released in November 2008, Left 4 Dead has proven to be one of the biggest hits for Valve since CSS servers, eclipsing Team Fortress 2 servers in the popularity contests.

There are two main types of gameplay for Left 4 Dead game servers. One where you work with a team and other people online - campaign based. The most popular online mode is versus mode, where teams split into two teams of four- survivors and zombies. Survivors have the role of completing the level The zombies role is to hunt out the humans using zombies such as the Tank, Smoker, Hunter and Boomer.

Other than the human zombies, computer controlled infected also attack humans. If you have watched the movie 28 Days Later, you will probably be familiar, hunting in packs called hordes they will kill you in numbers. They can climb ladders and scale objects with relative ease and break through walls and doors and like to be attracted to flash lights and loud noises like car alarms and gun fire.

Less common infected are scattered around maps to keep you on your toes.

The witch rarely appears one or two times on a map- and you'll not come across her bad side as long as you don't point the flash light at her or get too close. She is normally located just off the normal route, but can easily be found by accident and disturbed.

We also have the playable infected which can be played in versus mode. The boomer is perhaps the most annoying- vommiting a bile at you that temporarily blinds you and also attacts the infected. Thus it is well worth keeping your distance from him and his vommit. A skilled marksman would pick him off from distance as he is slow and has low health, but when he is killed he will explode covering any survivors close enough to cover them in bile as well.

In terms of speed, the hunter is like the fast zombies on HL2. In terms of looks they don't take the appearance of a zombie, more like a chav! He is quick and agile and will climb a wall with ease. Like a cat unless you knock him off, he'll pin down and maul survivors to death. However he doesn't have much health so can be taken out easily.

With his long tongue, the smoker sneaks from a distance. Similar to the barnacle in Half Life 2, another survivor must free you once you are caught. In addition, they choke their victim with a smoke, impairing their vision. They will cough frequently to let you know of their presence in an area.

Before you move onto the newest online play- Left 4 Dead 2 servers, make sure you can handle the tank . The tank the biggest and badest of the infected you are just going to have to play the game to discover just how big and nasty these guys are as words cannot do him justice!