Sudoku Puzzle is a free online version of the classic game that you can start playing right away in your browser, without registering.
The game features four difficulty levels in classic mode: Easy for newcomers, Medium for those who want to improve their skills, Hard for more experienced players, and Expert for true puzzle enthusiasts. There are also additional modes that add new rules: X-Sudoku with diagonal restrictions, Windoku with extra zones on the grid, Killer Sudoku where you need to reach a certain sum in cell groups, and Kropki with markers showing the ratios and differences between neighbouring cells.
Each puzzle has a unique solution that can be found using logic alone, without any guesswork. If you encounter difficulties, it means you missed a step, which you can always identify and correct.
Sudoku Puzzle also offers a competitive element: leaderboards show rankings based on level, score, and wins. Personal profiles keep track of your gaming history and detailed statistics. The chat allows players to connect, exchange strategies, and challenge one another.
How to play
Your task is to fill a 9×9 grid with numbers from 1 to 9 in such a way that each number occurs only once in every row, column, and each 3×3 section. Some cells are already completed — they serve as your initial hints.
Start with those cells that have the most filled neighbours; this will make it easier to determine the right number due to fewer possible options. As you fill in the cells, the choices for the surrounding ones become more limited, revealing the solution step by step through logical deduction.
Use the notes function to jot down potential numbers in a cell and cross them out as the grid fills. This tactic is particularly helpful on the Hard and Expert levels.
Special modes introduce additional rules: in X-Sudoku, numbers must also be unique on both main diagonals; in Windoku, additional highlighted areas follow the same rule of uniqueness; in Killer Sudoku, groups of cells must sum up to a specified value; in Kropki, markers between cells indicate relationships — a white dot means the numbers differ by 1, a black dot means one number is double the other.
Sharpen your mind!