Sujiko

Sujiko is a logic-based number placement puzzle designed by Jai Gomer of Kobayaashi Studios. It is played on a three by three grid of nine cells, with four circled clue numbers positioned where the corners of the four two by two quadrants of the grid meet. Each circled clue gives the sum of the four numbers occupying the quadrant surrounding it. To solve the puzzle, a solver places the digits one through nine, each used once, into the nine cells so that every quadrant sum matches its circled clue simultaneously, using elimination and arithmetic reasoning rather than guesswork. Unlike sudoku, sujiko has no row or column constraint beyond the placement of each digit exactly once across the whole grid, which keeps the puzzle compact and quick to solve. The puzzle gained mainstream popularity in Britain, appearing as a regular puzzle feature in newspapers including The Times, The Daily Telegraph and The Sun, which introduced it to a wide general audience beyond dedicated puzzle enthusiasts.