There may be no other game released this year that can promise as consistently a thrilling and hilarious multiplayer experience as this. Out of Valve's ongoing attempts to bridge the gap between its highly-tuned single-player titles and the necessarily chaotic nature of multiplayer gaming comes Left 4 Dead, whose AI director and tight four-player cooperative play create a team-based atmosphere that is both coherent and unpredictable, even upon multiple playthings of the same campaign.
Hitting the right notes between necessary player-to-player interaction and the independence demanded by a first-person shooter, Left 4 Dead is possibly the most accurate video game representation of the classic cinematic zombie invasion to date, even as its antagonists operate quite differently to their traditionally sluggish filmy counterparts. Much of this is due to the group dynamics that the game fosters, coaxing out emergent archetypes like "that idiot who accidentally makes a noise and alerts the entire horde" or "the sole survivor who somehow staves off wave after wave and makes it to the chopper."
On top of that, the seemingly endless supply of brief character quips continues Valve's recent trend of summoning up surprising depth to characters who exist outside of any substantial defined narrative.