Space Turtle Equation

Description from the publisher: This is a two-player trick-taking game in which players are divided into two roles: the "Turtle Theorist," who claims the universe is a turtle, and the "Astronomer," who argues that it is not a turtle. The game's greatest feature is that players can play cards face down, and their card strength is hidden from their opponent. At the start of the game, the Turtle Theorist places a card face down and sets the value "X." This "X" determines the card's strength when played face down. While the opponent, the Astronomer, does not know the exact value of "X," they can infer its value to some extent based on whether the trick is won or lost. (For example, the Astronomer plays an "8" card, the Turtle Theorist plays "X," and the Turtle Theorist wins the trick → "X" is determined to be 8 or greater.) By repeating this process, the range of "X" values is narrowed down, and ultimately, the Turtle Theorist must fulfill his bid, while the Astronomer must prevent his opponent from fulfilling his bid.