Hearts of Iron IV is a grand strategy video game developed by Paradox Interactive, set during the time of World War II. Players take control of a nation and manage its military, economy, and diplomacy from 1936 to 1948. The game emphasizes historical accuracy and allows players to alter the course of history through strategic decisions. In Hearts of Iron IV, players can choose from various countries, each with unique strengths and challenges. The game features complex mechanics, including resource management, technology research, and military tactics, enabling players to engage in large-scale battles and create alliances or rivalries with other nations.