Left 4 Dead was released by Valve in 2008 as a co-operative first-person shooter about four Survivors fighting through hordes of Infected. Its audio design was central to the experience, with short cues warning players, confirming actions and building dread in the middle of chaotic fights. Clips lifted from the game later spread across forums, videos and soundboards, where they became shorthand for zombie horror outside the original matches. This short effect remains popular with editors because it carries that familiar tension in under two seconds and needs no context to work.