The siren comes from Konami's Silent Hill, first released in 1999, where an air raid siren warns that the fog covered town is slipping into the Otherworld, a rusted and bloody alternate dimension. The sound became one of the series' most recognisable cues and was carried into later games and the 2006 film adaptation. Clips of the wail spread through horror forums, YouTube edits and soundboards, and creators now use it far beyond the games as a universal signal that reality is turning hostile and something terrible is about to happen.