Sudoku is a simple, addictive game of logic that has taken the world by storm! Use reasoning and patience to solve the number grid, without the need for math skills or guesswork. The rules of this mind-boggling puzzle game are simple: Fill in the grid so that every row, column and 3x3 box contains each of the digits 1-9 only once. Sound simple enough? Version 1.15 includes 10 difficulty levels, auto save/load, undo, pencil marking, auto pencil mark option.