Left 4 Dead is Valve's 2008 co-operative first-person shooter about four survivors fighting hordes of infected. Its common infected use short, feral vocalisations for attacking, being hit and dying, designed to be readable in chaotic fights without any dialogue. Clips of those death sounds later spread through gaming forums, YouTube montages and soundboards as standalone effects. The clip remains popular because it is brief, unmistakably a zombie, and works outside the game as a clear audio cue for any undead character being defeated.