Sudoku

Puzzle solved! 🎉

Tap a cell, then tap a number.

Objective of Sudoku

In the game of Sudoku, your objective is to fill every empty cell in a 9×9 grid so that each row, each column, and each 3×3 box contains the digits 1 through 9 — with no repeats. Can you solve the puzzle without making any mistakes?

Sudoku's Gameboard

On the screen above you'll see a 9×9 grid, partially filled with numbers. Tap any empty cell to select it (it will highlight), then tap a number on the pad below to fill it in. To remove a number you've entered, tap the cell and then tap "Erase."

How to Play Sudoku

Every Sudoku puzzle has three rules. Every row must contain the digits 1 through 9 exactly once. Every column must contain the digits 1 through 9 exactly once. And every 3×3 box must contain the digits 1 through 9 exactly once.

Each puzzle starts with a set of fixed numbers. Use these fixed numbers as clues to help you figure out where to place all of the other numbers.

Keep going until every cell is filled in. If you've solved the puzzle correctly, a win banner will appear to celebrate your success.

Every puzzle on Spiffytap has exactly one solution and can be solved using pure logic. No guessing required!

Strategic Tips for Sudoku

  • Start with the easiest cells: Look for empty cells amid rows, columns, and boxes that are almost full. The more numbers already in place, the fewer options remain for the empty cells.
  • Scan intersecting rows and columns: Make deductions by checking both the row and the column that pass through an empty cell. For example, if you see that an empty cell's row already contains 1, 2, and 3, and that its column already contains 4, 5, and 6, then you know that the empty cell itself must contain either 7, 8, or 9.
  • Never guess: Every cell has a logically provable answer — you just have to find it. A wrong guess, especially early on, can quietly corrupt the rest of the puzzle and undermine all your hard work.

Levels of Difficulty

You can choose between two levels of difficulty: "Easier" puzzles can be solved using straightforward logic, while "Harder" puzzles have fewer starting numbers and require a bit more patience to crack.

Fun Fact

The numbers in Sudoku are just symbols — they could just as easily be letters or shapes. No arithmetic involved!