Sudoku

About the game

Fill the nine-by-nine grid so that every row, every column and every three-by-three box contains the digits 1 to 9 exactly once. Some cells are given, the rest are yours to deduce. A fresh puzzle is generated every time, at the difficulty you pick.

The tools are the ones a solver wants. Notes lets you pencil small candidate numbers in a cell. Auto fills every empty cell with its legal candidates at once, and you then cross them off by hand. Picking a number highlights all the matching digits on the board, conflicts glow red, and Hint reveals one cell for you (it is turned off on the hardest level). The game keeps a timer, counts mistakes and hints, and saves your puzzle in the browser, so you can close the tab and come back.

Playing it here

Click Play, pick a difficulty if asked, then select a cell and press a digit. The buttons under the grid do the same with the mouse or a finger.

Controls

A few things worth knowing

Start with singles. Look for rows, columns or boxes that are missing only one digit.

Use notes on the hard levels. Auto-candidates save time, but trim them yourself.

Watch the red. A glowing conflict means a wrong digit somewhere, not just in that cell.

Credits and licence

Sudoku is one of the games in LittleJS Arcade, a collection by Frank Force built on his open-source LittleJS engine and released under the MIT licence. The pictures are drawn in code and the sounds are synthesised, so the game has no image or audio files. The author's repository includes AI-assistant guidance files, so the collection was written with the help of AI tools. The licence text is linked from this page and the source code is on GitHub.