Left 4 Dead was released by Valve in 2008 as a four-player co-operative first-person shooter about surviving a zombie outbreak, with a sequel following in 2009. Its short UI cues, weapon sounds and infected noises became highly recognisable to players who spent hours in campaign and Versus modes. As soundboards and short-form editing grew, fans isolated individual in-game effects like this one for quick reuse outside the game. It remains popular because it instantly signals Left 4 Dead to anyone who played it, without needing dialogue, music or a long build-up.