Hearts of Iron is a series of grand strategy video games developed by Paradox Interactive. Set during the tumultuous period of World War II, players take on the role of a nation, managing its military, economy, and diplomacy. The game emphasizes historical accuracy and allows players to alter the course of history through strategic decisions. In Hearts of Iron, players can choose from various countries, each with unique strengths and challenges. The gameplay involves planning military campaigns, researching technologies, and engaging in political maneuvering. The series is known for its depth and complexity, appealing to fans of strategy and history.