Daily Sudoku Guide
About Diagonal
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Daily Sudoku Guide
About Diagonal
Diagonal Daily Sudoku for 2026-01-21
Play today's Hard Diagonal Daily Sudoku online for 2026-01-21 on Puzzella. Diagonal Daily Sudoku adds an extra constraint to the standard grid, making it a stronger fit for players who already enjoy classic Sudoku and want a more tactical daily challenge.
How Diagonal Daily Sudoku works
- Standard Sudoku rules still apply across every row, column, and 3x3 box.
- The main diagonal must contain 1 to 9 without repeats.
- The anti-diagonal must also contain 1 to 9 without repeats.
Variant notes
Why Diagonal Sudoku feels different
- Diagonal Sudoku increases cross-board interactions, so every placement affects more of the grid.
- It works well for players who already solve classic Sudoku comfortably and want an extra layer of logic.
- The diagonal constraint makes candidate tracking and cross-checking more important than in standard Sudoku.