Double Sudoku
Double Sudoku, also known as Twodoku, joins two grids at a corner box with both diagonals constrained in the lower-right grid.
Double Sudoku
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Keyboard: 1–9 enter · arrows move · N notes · Backspace clear · Ctrl+Z undo
How to Play Double Sudoku
- Solve two 9×9 grids sharing one corner 3×3 box.
- Every row, column and 3×3 box in each grid contains 1 to 9 exactly once.
- Both diagonals of the lower-right grid also contain 1 to 9 exactly once.
- Shared cells obey both grids; empty gaps are not playable.
Tips for Solving
- Use the shared corner to transfer deductions between grids.
- Check the lower-right diagonals when eliminating candidates.
- The diagonal colour takes priority where it crosses the shared box.
Frequently Asked Questions
Is Double Sudoku free to play?
Yes. Every Double Sudoku puzzle on Sudoku Shrine is free in your browser, with no account or download.
Does every Double Sudoku puzzle have one solution?
Yes. Each puzzle is checked by a solver so it has exactly one solution and can be solved by logic alone.
Which difficulty should I start with?
Start with Easy to learn the layout, then move to Medium and Hard once scanning and notes feel natural.
Is my progress saved?
Yes. Your entries and notes are saved in this browser, so you can close the page and continue later.