Hearts of Iron IV is a World War II grand strategy game developed by Paradox Interactive and released in 2016, where players control a nation through diplomacy, industry, and warfare. The declare war cue plays inside the game when one country formally begins hostilities against another, marking a major turning point in a campaign. As gameplay clips and strategy memes spread online, creators began lifting the sound for edits outside the game, using its dramatic weight to signal conflict, rivalry, and high-stakes decisions in their own videos.