K-Doku 7x7, a Sudoku game, twists traditional rules. On a 7x7 grid, the player fills every cell with a number so that 1 to 7 are represented once in each row and column. They use mathematical operators to guide their actions. They combine numbers in a smaller area to create a specific sum. With an upper-left corner operator of 13+ in a three-number zone, for example, they select three numbers that equal 13 when added together.
