Daily Sudoku X

What is Sudoku X?

Sudoku X (also known as Diagonal Sudoku) adds two diagonal constraints to classic Sudoku. In addition to the usual row, column, and box rules, both main diagonals must also contain the digits 1-9 without repetition.

The two diagonals are:

• Main diagonal: cells from top-left to bottom-right

• Anti-diagonal: cells from top-right to bottom-left

The center cell sits on both diagonals and must satisfy both constraints. This extra layer of logic creates more interdependencies and requires careful attention to diagonal patterns.

Daily Sudoku X Format

A fresh Sudoku X puzzle is published every day at midnight UTC. Each puzzle is uniquely numbered from launch, creating a persistent timeline you can track and share.

Your streak counter tracks consecutive days completed. Unlike practice mode, each daily is a shared experience—everyone worldwide solves the same puzzle on the same day.

How to Play

Fill the 9×9 grid so each row, column, 3×3 box, and both diagonals contain all digits 1-9 without repetition. The puzzle provides some filled cells (givens) to start.

Diagonal cells are subtly shaded to help you track the constraint. Use elimination: check which digits already appear in each cell's row, column, box, and diagonals. If multiple candidates remain, use Notes Mode to pencil them in.

The Check button highlights conflicts. Your timer pauses when you switch tabs. Progress saves locally using IndexedDB—no account needed.

For detailed rules and solving techniques, visit the Sudoku X hub page.