A (possible?) game.
OK, imagine a Tic-Tac-Toe board. But rather than claiming squares based on order of choice, the player needs to answer a trivia question, to decide who claims the squre.
Isn't that just Hollywood Squares?
Mystic T-Square does bear some resemblance to the old game show, yes. However, it expects only one player to answer questions.
Plus, the other player can slide the squares, like tiles in a 15-puzzle. The other player gets that job.