Samurai Sudoku
Score
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Mistakes
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Time
00:00
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Easy · Samurai · 5 sub-grids0%
How to play Samurai Sudoku
Five overlapping 9×9 Sudoku grids. Each sub-grid must independently satisfy standard Sudoku rules (1–9 in each row, column, and box). Where two sub-grids share a 3×3 corner box, that box must satisfy both grids simultaneously.
Full guide →
Five overlapping 9×9 grids sharing corner boxes
Easy
Samurai Sudoku Easy
Medium
Samurai Sudoku Medium
Hard
Samurai Sudoku Hard
Expert
Samurai Sudoku Expert
What is Samurai Sudoku?
Samurai Sudoku consists of five interlocking 9×9 grids arranged in an X shape — one central grid and four corner grids, all sharing a 3×3 box where they overlap. Each of the five sub-grids must independently satisfy standard Sudoku rules. Solving one sub-grid often provides clues that unlock another. The complete puzzle spans a 21×21 grid.
At a Glance
| Constraint type | 5 Overlapping Grids |
| Typical givens | ~30 per sub-grid |
| Difficulty rating | ★★★★★ 5/5 |
| Avg. solve time — Easy | 45 min |
| Avg. solve time — Medium | 90 min |
| Avg. solve time — Hard | 150 min |
| Avg. solve time — Expert | 240 min |
How to Solve Samurai Sudoku
| Technique | What it does | Level |
|---|---|---|
| Sub-Grid Independence | Each of the five 9×9 sub-grids satisfies standard Sudoku rules independently. Solve each one using all standard techniques. | Beginner |
| Overlap Box Exploitation | The four corner boxes where sub-grids meet are shared between two grids. Any digit placed in a shared box eliminates that digit from two sub-grids at once. | Intermediate |
| Cross-Grid Cascade | Completing a corner box in the central grid forces values in the corresponding corner grid's box, which may cascade further through that grid. | Intermediate |
| Shared Box Forcing | When a shared box is nearly complete, use both sub-grids' row and column constraints to force the remaining digits. | Advanced |
| Global Number Counting | Across all five sub-grids, each digit 1–9 appears 5×9=45 times total. This global count can confirm placement decisions near the end. | Advanced |
Average Solve Times
Easy
45 min
Medium
90 min
Hard
150 min
Expert
240 min
Frequently Asked Questions
What is Samurai Sudoku?
Samurai Sudoku is a variant consisting of five overlapping 9×9 Sudoku grids arranged on a 21×21 board. One grid occupies the centre, and four grids are placed at the corners with their inner 3×3 boxes overlapping the centre grid's corner boxes. All five grids must be solved simultaneously.
How do the overlapping boxes work?
Each of the four outer grids shares one 3×3 box with the centre grid. Any digit placed in a shared box satisfies the constraint for both grids simultaneously. This means information flows between grids through the shared boxes — solving one grid's corner often directly advances the centre grid.
Do all five grids have standard Sudoku rules?
Yes. Each of the five 9×9 grids individually follows all standard Sudoku rules: every row, column, and 3×3 box within that grid must contain 1–9 exactly once. The only interaction between grids is through the shared corner boxes.
Is Samurai Sudoku harder than regular Sudoku?
Samurai puzzles take significantly longer than single-grid Sudoku simply due to scale — you're solving five grids. Individual difficulty can range from easy to expert. The cross-grid interactions through shared boxes add a satisfying extra layer that single-grid Sudoku doesn't offer.
What is the best approach to Samurai Sudoku?
Work on all five grids simultaneously rather than trying to complete one before moving to another. When you get stuck on one grid, the shared boxes often provide a breakthrough from a neighbouring grid. Scan all five grids for hidden singles after every placement in any shared box.
How long does Samurai Sudoku take to solve?
Easy puzzles take 25–45 minutes. Medium puzzles run 45–90 minutes. Hard and expert puzzles can take 2–4 hours. The time is primarily driven by scale — five full grids — rather than by individual deduction difficulty.