Expert Samurai Sudoku

Five overlapping 9×9 grids share corner boxes. Solve all five simultaneously — each shared box belongs to two grids at once.

Easy Medium Hard Expert

The hardest five-grid Samurai puzzle on Sudoku.by. Intricate shared-box interactions — multi-grid forcing chains required. No guessing.

Score
-
Mistakes
0/3
Time
00:00
4
7
5
1
5
7
1
6
2
1
5
6
3
5
4
3
6
8
6
9
7
4
8
3
5
6
5
1
6
1
9
5
7
3
2
5
7
4
3
8
7
9
3
2
5
9
8
2
4
9
1
2
4
6
5
8
9
2
8
4
4
1
7
9
8
9
4
8
6
4
8
3
4
7
6
2
6
6
9
7
7
3
9
7
9
5
8
2
1
8
9
8
9
6
6
7
9
5
6
7
8
8
6
2
9
8
1
← Try Hard
Expert · Samurai Sudoku · 5 sub-grids 0%
How to play Samurai Sudoku
Five overlapping 9x9 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 3x3 corner box, that box must satisfy both grids simultaneously. Solve sub-grids with the most clues first, then use shared boxes to unlock others.
How to Play Samurai Sudoku →

What is Samurai Sudoku?

Difficulty
★★★★★
5/5
Constraint Type
5 Overlapping Grids
Typical Givens
~30 per sub-grid
Avg. Solve (Expert)
240 min

Solving Techniques for Expert Level

Technique Description 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 Time by Difficulty

Easy
45 min
Medium
90 min
Hard
150 min
Expert
240 min
Want a full walkthrough of rules, strategies, and solving steps? How to Play Samurai Sudoku →

Frequently Asked Questions — Expert Samurai Sudoku

Is expert Samurai Sudoku the hardest puzzle format on the site?
Expert Samurai Sudoku is the most time-intensive format — five full Sudoku grids with minimal givens, all interlinked through shared overlap boxes. It demands complete mastery of standard Sudoku techniques applied simultaneously across five grids.
Can expert Samurai Sudoku be solved without guessing?
Yes. Every expert Samurai puzzle on Sudoku.by has a unique logical solution. The solving path may be extremely long and require advanced techniques like X-Wings and forcing chains applied across sub-grid boundaries, but it is always logically derivable.
What advanced strategies work in expert Samurai Sudoku?
Multi-grid forcing chains: a digit placement in sub-grid A propagates through a shared box into sub-grid B, which forces a digit in B's own rows and columns, which then feeds back into the shared box with sub-grid C. Following these cross-grid chains is the defining skill of expert-level Samurai solving.
How should I organize my solving approach for expert Samurai Sudoku?
Treat the five sub-grids as a dependency graph. Identify which sub-grids share boxes with each other, and prioritize solving the shared boxes first — they create the most cross-grid propagation. Keep a running list of which cells in each shared box are resolved versus open.
How long does expert Samurai Sudoku take?
Expert Samurai Sudoku takes most players 90–180 minutes or more. If progress stalls, focus on the center grid — it shares boxes with all four corner grids, making it the highest-leverage sub-grid to advance at any point in the solve.

More questions? See the full Samurai Sudoku guide.