Arkham Horror is a cooperative board game set in the fictional universe created by H.P. Lovecraft. Players take on the roles of investigators who work together to stop ancient cosmic entities from awakening and causing chaos in the city of Arkham, Massachusetts. The game features a mix of exploration, combat, and resource management as players encounter various challenges and horrors. The game is played on a modular board that represents different locations in Arkham and includes various scenarios and expansions. Players gather clues, fight monsters, and attempt to seal or close gates to other dimensions, all while managing their sanity and health. The game emphasizes teamwork and strategy, making it a popular choice for fans of horror and adventure.