Hearts of Iron IV is a Second World War grand strategy game from Paradox Interactive, released in 2016, in which players guide a nation through diplomacy, industry and war. Its event system regularly interrupts play with historical and alternate-history developments, and the accompanying notification sound has become shorthand for important in-game news among strategy fans. Outside the game, editors reuse it to frame announcements, updates and jokes as if they were official bulletins, keeping it familiar to anyone who has watched HOI4 content online.