Sudoku is played with 9x9 grid, divided into 3x3 subgrids called "regions". The object is to fill empty cells with numbers between 1 and 9, so that number should appear only once on each row, column and region. Easy, Medium and Difficult games have a unique solution. Nightmare games have multiple solutions. Many settings: - for Tablets and Phones - autosave - statistics - unlimited Undos - mode Easy, Normal, Difficult, Nightmare