The objective is to fill a 9x9 grid with digits so that each column, each row, and each of the nine 3x3 sub-grids that compose the grid contains all of the digits from 1 to 9. Whether you'd like to relax or keep mind active pass your free time in a pleasant way! Get a small stimulating break or clear your head with Sudoku. Choose any level you like. Play easier levels to exercise your brain, logical thinking and memory, or try hard levels to give your mind a real workout. Features 6 perfectly balanced levels of difficulty: from very easy to expert Unlimited amount of well-formed puzzles Selected digit and various other highlighting options Pencil marks with auto-update Classic 9x9 grid Simple and intuitive design Minimalist package size - just 2mb Auto check for puzzle rules Auto-save/restore Unlimited Undo and Redo Does not require internet connection - works offline Day/Night color themes Train your brain anywhere, anytime!