The idea for Left 4 Dead originated from a Counter-Strike: Condition Zero mod called "Terror Strike," created by Turtle Rock Studios. In this mod, a small group of players armed with guns had to defend against larger number of enemies who could only use knives. Turtle Rock realized the fun of this concept and, with Valve's approval, began developing it into the cooperative shooter that would become Left 4 Dead. Turtle Rock officially began developing the game, which was initially funded by Valve, in 2005. Valve later acquired Turtle Rock Studios, with the company becoming "Valve South". Valve's involvement led to the project's expansion, with Chet Faliszek joining as the lead and more than 100 Valve employees contributing to the game's development.

good cold stream beta map! It's a lot different than the current cold stream :)

this stream be cold