L4D is the zombie game you have been waiting for. Bring friends!
All you have to do is to search for a game and pick a person, then cooperate with the other players in 20 fun and scary levels, divided up into four chapters.
There isn't much to say about the game other than you will be thrown right into the action from the start. It doesn't take many minutes to learn how to act accordingly to the different zombies you encounter thanks to the simple tips displayed as you progress.
What makes the game stand out, is what Valve calles the "AI director". The zombies wil always be attacking from new places so the game has incredible replay value!
For full details just play the game. Its the most fun you will have in a while.