Sudoku is the world's most popular logic puzzle. It's fun, infuriating, and absolutely addictive! The rules to the puzzle, as with all great puzzles, are deceptively simple and easy to understand. It's a puzzle of reasoning and logic - no maths involved - but that's not to say that Sudoku won't give your brain a workout. With four levels of puzzles, ranging from gentle through moderate and tough to diabolical, there are plenty of challenges for novices and experienced Sudoku-solvers alike.