Sudoku Challenges is a logic-based, combinatorial number-placement puzzle. The objective is to fill a 9 × 9 grid with digits so that each column, each row, and each of the nine 3 × 3 sub-grids that compose the grid (also called "boxes" or "blocks") contain all of the digits from 1 to 9. Each puzzle will start at a partially completed grid, which has a single solution. Sudoku, Sudoku Game, Logic Puzzle, Brain Training, Number Puzzle, Number Game, Brain Exercise, Arcade Game, Mobile Game, Puzzle Game, Number Placement, 9x9 Grid, Classic Puzzle, Number Game, Brain Workout, Concentration, Memory, Cognitive Function, number game, number puzzle, brain training, sudoku challenge, logic, mobile game, arcade, numbers