Samurai Sudoku - Play Free Online

Samurai Sudoku (you might also hear Gattai-5 or 5-grid sudoku) takes five standard 9×9 Sudoku grids and arranges them in a cross pattern. Four corner grids surround a center grid, and each corner shares one 3×3 box with the center. The result: 369 cells total, making it over 4.5 times larger than a standard 81-cell grid.

What makes it special is the overlapping structure. Cells in those shared 3×3 boxes must work for both grids at once. Solve a digit in one grid and it immediately reveals something about its neighbor - a cascade of deductions spanning all 369 cells.

Each of the five 9×9 grids follows normal Sudoku rules: every row, column, and 3×3 box within a grid gets digits 1–9 exactly once.

Here's the twist: four pairs of grids share a 3×3 box. Any cell sitting in an overlap must satisfy constraints from both grids simultaneously. These shared boxes are what link all five grids into a single puzzle.

Every Samurai Sudoku puzzle has exactly one solution. The overlapping regions act as bridges between grids, making sure the whole thing can be solved through pure logic.

Begin with the center grid. It shares boxes with all four corners, so it's the most constrained region on the board. Every digit you place in those overlap boxes constrains two grids simultaneously - maximum bang for your buck.

Then branch outward through the overlaps. Solving cells in a shared box sends constraints rippling into the adjacent corner grid. Think of those overlap boxes as bridges: crack one side and you'll find clues waiting on the other.

Standard techniques (scanning, crosshatching, naked and hidden singles) work within each grid. On harder puzzles, watch for cross-grid eliminations - when a digit is locked in one grid's overlap, it's settled in the neighbor grid too, and that can trigger a chain reaction.

Hit the center grid first. Four shared boxes means more constraints than anywhere else on the board, so that's where progress comes fastest.

Treat overlap boxes as leverage. Every time you place a digit in a shared region, jump to the adjacent grid and check for new singles or eliminations. That back-and-forth is the engine of efficient solving.

Don't try to finish one grid before touching another. Samurai Sudoku rewards grid-hopping. A dead end in one grid often opens up after you make progress in its neighbor through the overlap bridge.

Regular Sudoku: one grid, 81 cells, three constraint types. Samurai: five interconnected grids, 369 cells, plus overlap constraints linking everything together. It's a much bigger puzzle and takes considerably more time.

The logic underneath is still the same - placing 1–9 through elimination and deduction. Overlap regions add strategic depth without extra complexity, since cells in shared boxes actually give you more information to work with. Plenty of solvers find the cross-grid deductions the most satisfying part.