Pocket-Lint writes: "Valve is widely regarded as one of the best videogame developers active today. As creators of Half-life, Half-life 2, and Left 4 Dead, and buying up the mod teams responsible for Portal, Counterstrike, Team Fortress and Day of Defeat, the company has established itself a firm place in the pantheon of game creators, as well as in the hearts of gamers.
Valve launched its co-operative zombie shooter, Left 4 Dead, to a rapturous reception in late 2008. Gamers loved its balance, the way the game adapted to good or poor performance from the players, and its visceral combat. However, earlier this year, Valve pulled out a surprise - a prequel, less than a year after the original was released."