Left 4 Dead was released over two months ago for the PC and Xbox 360, and it was quickly labeled a success and attracted a large base of players which still thrives to this day. That shouldn't be all that surprising since the game combines two of gamers' favorites things: zombies and things that kill zombies. Of course the game then goes that extra mile by allowing four people to take on an entire town of the Infected hordes. The whole game is structured so that you must rely on your teammates in order to survive; there are even special zombies that render you useless until an ally comes to rescue you.
This all works well enough when you're playing with some people you actually know already. It's when you can't find three other people to join you in your zombie-killing fun, and you're forced to play with random people on the internet that things really get interesting. That's when you discover that some people online may have a different goal other than to just play a game and have some fun.
Here's a handy guide to some of the people you can expect to encounter while you're traipsing through Zombieville.