Commentary: Left 4 Dead

Raph Koster advises game designers to figure out what a game is about and then do nothing that would detract from that focus. I think that the developers of Left 4 Dead took that to heart. Every single aspect of the game system contributes to the creation of the best cooperative gameplay experience I've ever had. I'm a huge fan of pretty much any co-op experience, from side-by-side Gears of War battles to RTS comp stomps, but L4D easily takes the cake.

The general difficulty with co-op gaming is making everybody feel important. When there's a bunch of players fighting an AI, it's difficult to feel like your contribution was necessary. L4D gets past this by making it genuinely necessary that all four players work together (at least on the higher difficulties). If one player runs ahead, he will quickly get incapacitated or mobbed by zombies. If players don't stay conscious of each other's position, they'll end up losing due entirely to friendly fire. If players don't collaborate to use their resources effectively, they'll never make it past a end-of-campaign finale.

L4D does some cool things with the level design and art direction, but I think that the gameplay is its real strength, and the game stands as a testament to the idea that doing one thing and doing it well is a ticket to success.