Sudoku is one of the world's most popular logic-based number-placement puzzles. The objective is to fill a 9×9 grid with digits so that each column, each row, and each of the nine 3×3 sub-boxes contains all digits from 1 to 9. No math is required — just pure logical reasoning. Whether you are a complete beginner or an experienced solver, our free sudoku game offers four difficulty levels from Easy to Expert so you can always find the right challenge. Learn the complete rules to get started.
Sudoku is more than just a fun pastime — it is a proven form of brain training. Regularly solving sudoku puzzles helps sharpen concentration, improve memory, and develop logical thinking skills. Studies have shown that engaging in puzzles like sudoku can help keep your mind active and may contribute to long-term cognitive health.
Playing online sudoku also offers advantages over pen-and-paper puzzles. You get instant error checking, a built-in timer to track your progress, and an undo button for when you change your mind. Notes mode lets you pencil in candidate numbers without cluttering the grid, and hints are available if you get stuck. Plus, with unlimited free puzzles generated on demand, you will never run out of new challenges.
Whether you play sudoku to relax during a break, to warm up your mind in the morning, or to wind down before bed, it fits naturally into any routine. Each puzzle typically takes between 5 and 30 minutes depending on difficulty, making it ideal for both quick sessions and longer, focused play.
Classic Sudoku follows the traditional rules: fill the 9×9 grid so every row, column, and 3×3 box contains the numbers 1 through 9. With four difficulty levels — Easy, Medium, Hard, and Expert — there is always a sudoku puzzle matched to your skill level. Check out our tips and strategies to improve your solving speed.
Killer Sudoku adds a layer of arithmetic to the classic format. In addition to the standard rules, cells are grouped into colored cages with a target sum, and no number may repeat within a cage. This mode is perfect for players looking for an extra challenge that combines logic with basic addition. Try Killer Sudoku and see how you handle the added complexity.