Civilization IV is a turn-based strategy game developed by Firaxis Games and released in 2005. Players take on the role of a leader of a civilization, guiding it from ancient times to the modern era. The game involves exploring the world, founding cities, managing resources, and engaging in diplomacy or warfare with other civilizations. The game features a hexagonal grid for movement and a rich array of technologies to research. Players can choose from various civilizations, each with unique abilities and units. Civilization IV also introduced religion and great people, adding depth to gameplay and strategy.