Mission content bleeds into player faction headquarters in London, Seoul and the DUMBO neighborhood in Brooklyn, and into the game's transport network, along the subterranean branches of Yggdrasil in Agartha. The game uses a contemporary setting, borrowing heavily from the horror fiction genre and folklore, with a fog-ringed, zombie-infested New England fishing village for the novice player, mummies and cultists in Egypt for the mid-level player, followed by vampires and werewolves in Transylvania and ghosts, robots, Oni and an interdimensional occult cancer in Tokyo.

In the game, the player's character joins one of three world-controlling secret societies attempting to repel, mitigate or exploit the attack of Lovecraftian entities and other immortal beings in coastal Maine, rural Egypt, Transylvania, a quarantined section of Tokyo, a utopian community outside South Africa's Cape Town, and (planned) a section of the river Congo and to advance their society's agenda over that of the others. In 2017, The Secret World was relaunched as Secret World Legends. The Secret World uses a subscription-optional, buy-to-play business model, requiring players only to buy the game with no additional subscription fees, with additional benefits to those members still paying a subscription. Ragnar Tørnquist led development of the initial game for Funcom. The Secret World is a massively multiplayer online role-playing video game set in a modern-day real world under attack from occult forces.

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