Sudoku Puzzle Game — Play Online
Play a generated Sudoku puzzle. Fill every row, column and box with digits 1-4.
How to play
- Click a white cell to select it (it turns blue), then press 1–4 to enter a digit.
- Each row, column, and 2×2 box must contain the digits 1–4 with no repeats.
- Press Backspace or 0 to erase a digit you entered.
- Click 'Check' to see if any cells are wrong; click 'Reveal' to show the solution.
Fill the 4x4 grid so every row, column, and 2x2 box contains each of the digits 1–4 exactly once. Click a cell then type a digit (or use Backspace to erase).
How it works
This version of Sudoku uses a 4x4 grid divided into four 2x2 boxes. The rules mirror classic 9x9 Sudoku: place the digits 1 through 4 so that every row, every column, and every 2x2 box contains each digit exactly once. A set of starting clues is provided and the rest is pure deduction.
The 4x4 format is beginner-friendly and typically solvable without any guessing, making it a great introduction to Sudoku reasoning before attempting larger grids. Every puzzle has a unique solution derivable from the clues alone.
The two main techniques are elimination (a cell must be X because the row, column, or box already contains every other digit) and singles (only one digit is missing from a row, column, or box, so that digit must go in the empty cell). On a 4x4 grid these two techniques are usually sufficient to solve any puzzle completely.
Use this puzzle to practice systematic logical deduction, teach Sudoku rules to beginners, or fill a few spare minutes with a satisfying, completable challenge.
Worked example
Solve an empty cell using box elimination
- Look at the top-left 2x2 box: it already contains 1, 3, and 4.
- The missing digit must be 2, so place 2 in the empty cell of that box.
- Now check the row containing that cell: it has 2, 3, and 4 revealed.
- The missing digit for that row is 1 — place 1 in the remaining empty cell.
- Continue scanning rows, columns, and boxes for similar forced placements.
Every cell is filled correctly and the puzzle is solved.
Common mistakes to avoid
- Checking only the row or only the column when it is a box constraint that actually forces the digit.
- Placing a digit based on where it feels right rather than eliminating every other option first.
- Forgetting that each 2x2 box is an independent constraint in addition to rows and columns.
Key terms
- Given (clue)
- A digit pre-filled in the grid that cannot be changed; it anchors your deductions.
- Naked single
- A cell where only one digit is possible after eliminating what already appears in its row, column, and box.
- Box (region)
- One of the four 2x2 sub-grids that must also contain each digit exactly once.
Frequently asked questions
- Is every generated puzzle unique?
- Each new game generates a fresh random puzzle with a unique solution.
- How do I enter numbers?
- Click a cell to select it (it turns blue), then press 1–4 on your keyboard. Press Backspace or 0 to erase.