Samurai Sudoku

Samurai Sudoku is a free online Sudoku built from five overlapping 9x9 grids: one in the centre and one at each corner, arranged in the quincunx shape the puzzle is known for. Each grid follows the ordinary rules — 1 to 9 in every row, column and 3x3 box — but the four corner boxes are shared between two grids at once, so a digit placed there has to work in both. That is what makes it one 369-cell puzzle instead of five separate ones. The shared boxes are tinted green, and a zoom control lets you drop into one grid at a time or pull back to see all five. Eight levels, no download, no account.

How to play Samurai Sudoku

1. Tap any empty cell to select it, then tap a digit from 1 to 9 on the number pad. Arrow keys and number keys work on desktop.
2. Each of the five 9x9 grids follows the standard Sudoku rule: every row, every column and every 3x3 box must hold each digit from 1 to 9 exactly once.
3. The four tinted 3x3 boxes where the centre grid meets a corner grid belong to both of them. A digit there has to be legal in both grids at the same time — those boxes are where the puzzle is won or lost.
4. Use the − and + buttons to zoom. "Fit" shows all five grids at once for planning; the larger steps scroll so you can work comfortably inside a single grid.
5. A wrong digit is flagged in red right away — useful here, because a mistake in a shared box can otherwise send you down two grids before you notice. Fill all 369 cells to clear the level.

Tips

• Start in the overlaps. A shared box is constrained by two grids at once, so it usually has the fewest possibilities on the whole board and cracks first.
• Solve the centre grid early. It touches all four corner grids, so every digit you fix there feeds clues outward in four directions at once — whereas a corner grid only feeds back to the centre.
• Work at "Fit" zoom when you want to spot which grid is closest to finished, then zoom in to actually fill it. Trying to do both at one zoom level is what makes a Samurai feel slow.
• Treat each 9x9 as an ordinary Sudoku once its shared box is settled. The overlaps are the only thing that makes this different — the rest is technique you already have.
• This is a long sitting, so use the five hints sparingly and rely on undo instead. Progress is saved per level, and the counter in the header shows how many of the 369 cells are filled.

FAQ