fter working on Counter-Strike: Condition Zero under contract for Valve, Turtle Rock Studios had a couple of ideas in the works. One was a first-person wizard game that never got off the ground, while the other was a mod for Counter-Strike that transformed the counter-terrorists into bots who came at you in swarms and only attacked with knives. This was Terror-Strike, and it was the foundation of Left 4 Dead... Read more.