Hearts of Iron IV is Paradox Interactive's grand strategy game about World War II, first released in 2016, in which managing diplomacy, armies and industry can suddenly give way to open conflict. A declaration of war is one of its most consequential moments, so its accompanying cue has become instantly recognisable to strategy players. As gameplay clips and edited videos spread online, creators began lifting the sound from its original context and using it for fictional rivalries, online arguments and unexpected betrayals, keeping it popular because the stakes it signals need no explanation.