Sudoku is a simple number-based puzzle game played on a 9x9 grid that is divided into 3x3 subgrids. The goal is to enter a number from 1 to 9 in each cell so that each number appears only once in each column and row. In addition, each 3x3 subgrid may only contain one of each number. At the start of a new game, Sudoku fills in a random selection of cells for you. The number of cells depends on the difficulty level you use. Use the arrow keys to highlight individual cells and press fire button to fill in the editable cell.