About

The game

Sudoku is a logic puzzle played on a 9x9 grid. Fill the empty cells so that every row, every column and each of the nine 3x3 boxes contains the digits 1 to 9 exactly once. The givens are fixed, and a well-formed puzzle has a single solution you can reach by reasoning — no guessing required. Every puzzle on this site is checked to have exactly one solution before it ships.

How it works

• Tap a cell and then a digit on the number pad, or use the arrow keys and 1-9 on a keyboard.
• Delete clears a cell; undo, redo and restart are always available while you play.
• A digit that repeats in a row, column or box is highlighted as a clash — with a shape and icon, not only a colour, so it stays readable.
• Your completed puzzles and best times are saved in your own browser's local storage. There is no account and nothing is sent to a server.
• Clearing your browser data clears your progress — you can also reset it from the puzzles page.

The project

This game is part of a small, open collection of browser games. It is built to load fast, work on a phone as well as a desktop, and require no sign-up to play.