Sudoku is played on a 9x9 grid divided into nine 3x3 boxes. Some cells are pre-filled with numbers. Your goal is to fill every empty cell with a number from 1 to 9 so that each row, each column, and each 3x3 box contains all the digits from 1 to 9 exactly once. Click or tap an empty cell and enter a number. Use logic and elimination to determine the correct placement.
What difficulty levels are available in this Sudoku game?
This Sudoku game offers three difficulty levels: Easy, Medium, and Hard. Easy puzzles have more pre-filled cells (around 38-45), making them great for beginners. Medium puzzles require intermediate techniques like naked pairs. Hard puzzles have fewer given numbers and demand advanced strategies such as X-Wing and hidden triples.
What are the best strategies for solving Sudoku puzzles?
Start with scanning: look for rows, columns, or boxes that are nearly complete. Use pencil marks to note possible candidates for each cell. Apply elimination by removing candidates that conflict with existing numbers. Key techniques include naked singles (only one candidate left), hidden singles (a number can only go in one place within a row/column/box), naked pairs, and pointing pairs. For harder puzzles, learn X-Wing and Swordfish patterns.
What are the basic rules of Sudoku?
Sudoku has three simple rules: (1) Every row must contain the numbers 1 through 9 with no repeats, (2) Every column must contain the numbers 1 through 9 with no repeats, and (3) Every 3x3 box must contain the numbers 1 through 9 with no repeats. The puzzle starts with some numbers already placed, and there is always exactly one valid solution.
Can I play Sudoku on my phone?
Yes, this Sudoku game is fully responsive and works on smartphones and tablets. Tap a cell to select it and use the on-screen number pad to enter values. The game supports pencil notes, undo, error highlighting, and a timer on all devices. No app download is needed.
Modern Sudoku was designed by American architect Howard Garns in 1979 under the name "Number Place" and first published in Dell Pencil Puzzles & Word Games magazine. The puzzle was later picked up by Japanese publisher Nikoli in 1984, who gave it the name Sudoku, meaning "single number." It remained a niche favorite in Japan until 2004, when retired judge Wayne Gould introduced it to The Times of London, sparking a worldwide craze. Mathematicians have calculated that there are approximately 6.7 sextillion valid completed Sudoku grids, ensuring every puzzle presents a unique logical challenge. No guessing is ever required in a properly constructed Sudoku; pure deduction and elimination will always lead to the solution.
How to Play
Fill every cell in the 9x9 grid so that each row, column, and 3x3 box contains digits 1 through 9.
Click or tap a cell and type a number to place it.
Use pencil notes to track possible candidates for tricky cells.
Navigate with arrow keys and use logic, never guessing, to solve the puzzle.