How the online samurai sudoku game works

The generator first fills the whole 21×21 figure with a valid solution, then removes numbers one at a time and re-solves the entire samurai puzzle after every removal to prove that only one answer survives. Because the five grids share four 3×3 boxes, that check covers all of them at once — so you can always finish with logic and never have to guess.

Tap or click any empty square to select it, then press a number on the pad below the board or type 1-9 on your keyboard. Arrow keys move the selection between squares, and Backspace clears one. Building a samurai puzzle takes a few seconds longer than a single 9×9 grid, so you will see a short building message when you start a new game or change the difficulty.

Tools that make a samurai puzzle manageable

• Notes: pencil candidate numbers into a square, which matters far more on a 21×21 board than on a single grid.
• Hint: reveal one correct number when a corner grid refuses to open up.
• Check: find out immediately whether anything you have entered is wrong.
• Highlight conflicts: repeated digits in a row, column or box turn red as you type, in every grid they belong to.
• Zoom and fit: enlarge the board and scroll it on a phone, or fit the whole figure on screen on a laptop.
• Undo, timer and pause: step back through moves and stop the clock whenever you take a break.

Strategy: start in the shared boxes

The four overlapping 3×3 boxes belong to two grids at once, so they are the most constrained part of a samurai sudoku and usually give up digits first. Solve there, then carry what you learn outward into the corner grid and back into the centre.

After that, treat whichever grid you are in as an ordinary sudoku: scan rows, columns and boxes for the only place a digit can go, and use hidden singles and naked pairs when scanning dries up. Whenever you stall, look for a shared box that gained a number since your last pass — that is almost always where the next move is hiding.

Choosing a difficulty

If a samurai feels like too much in one go, remember your game is stored in this browser. Close the tab, come back later, and the same puzzle and clock are waiting for you.

• Easy: around 155 clues across the figure, with plenty of straightforward scanning moves.
• Medium: around 133 clues — the classic newspaper-style samurai.
• Hard: around 118 clues, where the overlaps do most of the work.
• Expert: around 107 clues for a long sitting; expect an hour or more.

Is this samurai sudoku free to play online?

Yes. Every puzzle is free, there is nothing to download, and you never need to register or sign in.

How many grids are in a samurai sudoku?

Five: one central 9×9 grid plus four corner grids, each sharing one 3×3 box with the centre. Together they form a 21×21 figure with 369 playable squares.

Does every online samurai puzzle have one solution?

Yes. Each puzzle is checked across all five grids during generation, so exactly one answer exists and pure logic is always enough.

Can I play samurai sudoku on my phone?

Yes. The board scales to your screen, there is a number pad under the grid, and a zoom control lets you enlarge the figure and scroll around it on a small display.

Will I lose my game if I close the page?

No. Your numbers, notes and timer are saved in your own browser, so you can pick up a long samurai sudoku exactly where you left it.