Samurai Sudoku: A Friendly Walkthrough
Five overlapping 9x9 grids in a single shape. Samurai is easier than its size suggests, once you know the rhythm.
Samurai sudoku looks like five sudokus that got into a fight. Five nine-by-nine grids, one in the centre and four overlapping its corners, sharing nine cells each. The result is a 21-by-21 shape that looks intimidating and is mostly easier than its size suggests.
The trick is that you are not solving five separate puzzles. You are solving one big puzzle with five overlapping constraints. The shared corner boxes belong to two grids at once. Anything you learn in one grid pays off in another.
How to start
Start at the four overlapping boxes. Each one sits inside two grids, which means every placement there has to satisfy twice as many constraints. The overlap boxes give up clues fastest because they are the most constrained.
After the overlaps, work the central grid. It shares all four of its corner boxes, which means almost every placement in the central grid feeds something back to one of the outer grids. The cascade is generous.
The shared-box mindset
When you place a digit in a shared box, two grids update. Walk both grids before moving on. Most beginners place a digit, scan the grid they were in, and miss the placement that just opened up in the other grid. You can lose half your time to that mistake on a long samurai.
Keep a finger on the shared boxes. Always look at them last in each scan; they are the most likely to surface a new single.
Pencil marks on a big board
Samurai puzzles are large enough that pencil marks demand more discipline than usual. Stale marks ripple across the whole grid, not just the unit you forgot to update. After every placement, sweep the shared boxes first. They are the place stale marks do the most damage.
On paper, samurai puzzles can be hard to mark cleanly because the cells are small. Digital play is friendlier for samurai than for any other variant.
What feels different
Time. A medium samurai is a 45-minute exercise, not a 20-minute one. The difficulty per cell is lower than a hard classic, but the cell count is much higher. Pace yourself.
Visual fatigue. Twenty minutes of scanning a 21-by-21 grid is more tiring than twenty minutes of a 9-by-9. Take a break after each grid. Stand up, look away, come back. The puzzle will not run off.
When samurai is most rewarding
Long flights. Quiet Sunday mornings. Anytime you want a single absorbing thing to do for an hour, with the satisfaction of five completed grids at the end. Samurai is the variant most likely to give you a sense of accomplishment per puzzle, because each grid is a milestone.
Where it stops being fun
If the puzzle drags. A samurai that takes ninety minutes because you got stuck halfway is no longer relaxing. If you are forty minutes in and have only finished one grid, the puzzle is harder than the label said and you are within your rights to put it down.
The best samurai puzzles are paced to keep you cascading from grid to grid. The worst ones isolate each grid and force you to solve them separately. Try a couple of sources and find the one whose rhythm suits you.
Play one on the samurai sudoku page, or browse the full variants catalogue for other shapes worth a Sunday morning.
Keep reading
- Hidden Pairs: A Deep DiveHidden pairs are the inverse of naked pairs and easier to miss. The scan flip that finds them, with a worked example.
- Sudoku and Stress: What It Actually DoesSudoku as stress relief is a small claim with a real basis. The displacement effect, the research, and when the puzzle is the wrong tool.
- Jigsaw Sudoku: A Friendly WalkthroughJigsaw sudoku replaces the 3x3 boxes with irregular regions. Once the visual chaos settles, it plays almost exactly like classic. Here is the plan.