ESRB Rating: Mature; Blood and Gore, Intense Violence, Language.
Left 4 Dead, the newest video game release by Valve Studios (the creators of Half Life, Counter Strike, and others), is a zombie apocalypse game for up to 4 players in local mode, or two teams of 4 in online play.
The game centers around 4 survivors: Zoe, Francis, Louis, and Bill, following their struggle for survival in a zombie apocalypse. If the 4 don't work together, they'll all die.
The missions are set in a movie format, with each of the 4 opening with a movie poster featuring the mission title, and characters. Each mission in itself is a seperate entity from the last.
The online gameplay (not rated by ESRB) isa fun alternative to solo gameplay, and is encouraged by the game. Online mode allows you to play as either the survivors, or as an infected (Tank, Boomer, Hunter, Smoker).
If you choose to play alone, the 3 other characters will be controlled by AI. They won't get ahead of you, or leave you to die, but if you're expecting them to clear entire waves of zombies, think again. The AI responds by how much effort you put into the game. They will kill enemies (unlike some games, where they'll just keep the enemy busy while you come to their aid), and they will help you and heal you when they see you are overrun or injured.
Online multiplayer is fun
Zombies, lots of zombies
Good AI interaction
Only 4 missions
Online teammates may suffer from lone wolf syndrome, where they leave you to die