Box Brain Sudoku
Rules › Diagonal
How to play Diagonal sudoku
Diagonal sudoku, also called Sudoku X, adds the two long diagonals as extra groups. A gentle first step beyond Classic.
Two extra lines.
The rules
- Classic rules apply: every row, column and 3×3 box holds the digits 1 to 9 once each.
- Both long diagonals also hold 1 to 9 once each.
Where to start
- The centre cell sits on both diagonals, so it is often the place to start.
- Treat each diagonal like a tenth and eleventh row: hidden singles work along them too.
Play Diagonal in Box Brain Sudoku
Every Diagonal puzzle in the app has exactly one solution and can be solved by logic alone, from Easy to Expert. Stuck? A hint first nudges you towards the right area, then names the technique and shows the move.