Cultistorm is a cooperative board game in which players play as Investigators of the special department of the Massachusetts State Investigation Bureau and the Miskatonic University, located in the United States of the early 20th century. The starting point of the game is when multitudes of frightening, disfigured strangers appear in the surroundings of Arkham. The ultimate goal of these Cultists is to summon their masters, the Great Old Ones, who are imprisoned in the great cosmic void.
The goal of the players is to fight the gathering Cultists and to prevent them from successfully completing their vile rituals. If the Cultists are able to summon the Great Old Ones, the Investigators must stop them in order to prevent the end of the world. The Investigators use spells, ancient wards, and relics of bygone ages, represented by symbols, to fight the Cultists and their masters.
During the game the Investigators will search for useful items, seek the help of locals, and learn Forbidden Knowledge. This will provide the Investigators with numerous actions that can support their fellow Investigators. However, the players can only use occult symbols in their own combat phases. This heavy reliance on the other Investigators necessitates strong cooperation. Constant communication and strategic thinking are key to defeating the Cultists and sealing all Locations.