Left 4 Dead is Valve's co-operative first-person shooter first released in 2008, built around four survivors fighting through campaigns of infected enemies, with a sequel following in 2009. Its dense mix of gunfire, infected calls, alerts and interface cues made individual sounds easy for players to recognise out of context. Fans later lifted short clips like this one onto soundboards, where they sit alongside other gaming staples such as Enemy Spotted and the FNAF Jumpscare Scream. The clip stays in use because a fraction of a second is enough to signal danger, panic or a perfectly timed gaming joke.