Cthulhu: The Great Old One is a Lovecraft-themed quick-play card game for 2 to 10 players. Each player is dealt cards until all cards in the deck have been dealt. Each player then makes pairs from the cards that player holds, making either Matched Pairs or Linked Pairs. Then each player, in turn, chooses one card at random from another player, in the hope of making more pairs. Players may choose to play one Horror or Cultist card at the end of their turn, after taking a card from another player, to cause an in-game effect. Once all cards have been paired (other than The Great Old One), then all players add up their total scores based on the pairs they created. Matched Pairs are worth two points, Linked Pairs are worth one point; and having all four cards of a Linked set is worth 4 points, no matter what order you have the two Pairs in. Horror cards are worth one point during the scoring phase. The player who ends the game holding The Great Old One loses the game, all other players compare scores to determine the winner. The Cultist card is a separate card which may be played instead of a Horror card at the end of a player's turn, and although it subtracts 1 point from the player's final score, if a player who has played the Cultist ends the game holding The Great Old One, they win the game!