Sudoku Variants Explained: Samurai, Butterfly, Gattai & Overlapping

Once you've solved enough standard sudoku, the puzzle world opens up into a surprising number of variations — and the most eye-catching of them all are the overlapping kinds, where several grids interlock into one giant puzzle. Samurai sudoku is the famous example, but it's just one member of a whole family: twin, butterfly, gattai, and other multi-grid layouts. This guide explains the main overlapping sudoku variants, how each one is built, and how they all trace back to the plain 9x9 grid you already know. If you've been curious about those intimidating multi-grid puzzles, here's your map.

For the broader catalogue of every variation — including non-overlapping types like killer and jigsaw — see our companion guide to the types of sudoku. This article zooms in on the overlapping family.

What makes a puzzle an "overlapping" sudoku

In a standard sudoku, you have one 9x9 grid. In an overlapping sudoku, two or more 9x9 grids share some of their cells, usually whole 3x3 boxes. The shared cells must be valid in every grid they belong to, which links the grids into a single connected solve. That shared-cell mechanic is the defining feature of the entire family — the variants differ mainly in how many grids overlap and where.

Every one of these still uses ordinary sudoku rules within each grid: each row, column, and box holds 1 to 9 with no repeats. Nothing new to learn rule-wise; you just track more grids.

Twin sudoku (two grids)

The simplest overlapping variant. Twin sudoku joins two 9x9 grids that share one or more 3x3 boxes. It's a gentle introduction to overlap logic — there's only one junction to manage, so you mostly solve two ordinary sudokus that hand a few digits to each other through the shared region. Krazydad and other publishers often offer these as a "twin" layout alongside the bigger samurai.

Samurai sudoku (five grids)

The headliner. Samurai sudoku uses five 9x9 grids — one center, four corners — arranged in an X, with each corner sharing a 3x3 box with the center. It totals 369 cells and is the most widely played overlapping variant by a wide margin. The four shared boxes are where the puzzle is won; a digit placed there helps two grids at once. We break down its structure in what is samurai sudoku and how to solve it in the samurai sudoku strategy guide.

If you want to start with the most popular overlapping puzzle, samurai sudoku is it.

Butterfly sudoku (four grids)

Butterfly sudoku overlaps four 9x9 grids in a 2×2 arrangement, sharing boxes where they meet in the middle. The result is more tightly interlocked than samurai — the grids share more cells with each other, so the cross-grid deductions come thick and fast. The name comes from the wing-like symmetry of the layout. It's less common than samurai but a favorite among solvers who enjoy dense overlap logic.

Gattai and super samurai (six or more grids)

"Gattai" is the Japanese word for "combined" or "joined together," and it's the umbrella term for these multi-grid puzzles in their original publishing tradition. Gattai-5 is, in fact, just another name for the classic five-grid samurai sudoku.

Beyond five grids, things scale up fast. Super samurai (sometimes "gattai-8" or larger) chains eight or more overlapping grids into sprawling constructions that can run to hundreds of extra cells. These are endurance puzzles — the logic is identical, but a single solve can take an hour or more. If you've conquered standard samurai and want more board, this is where to look.

Multi sudoku: the general term

"Multi sudoku" is simply the catch-all phrase for any puzzle combining more than one grid — twin, samurai, butterfly, gattai, and everything in between. If you see a puzzle described as "multi sudoku," expect overlapping grids of some arrangement. The solving approach is always the same: work one grid at a time and use the shared regions to pass information between them.

How to approach any overlapping variant

No matter how many grids are involved, the method that works for samurai sudoku works for all of them:

1. Solve the most-constrained grid first as a normal sudoku.
2. Copy every shared-cell digit into each grid that cell belongs to.
3. Move to the neighbor the overlap just helped, and repeat.
4. Use standard techniques — hidden singles, naked pairs, and the rest — grid by grid when overlaps run dry.

Learn it once on samurai sudoku and you can pick up butterfly, gattai, or any multi-grid puzzle without new theory.

Where to start

If overlapping sudoku is new to you, samurai is the right entry point — it's the most popular, the most documented, and the easiest to find at every difficulty. Try an easy samurai sudoku, get comfortable with the overlap rhythm, then branch out. And for variants that aren't about overlapping grids — killer, jigsaw, and more — the types of sudoku guide has the full picture.

Frequently asked questions

What are the main sudoku variants?

Sudoku variants fall into two broad camps: overlapping multi-grid puzzles (twin, samurai, butterfly, gattai) and rule-changed single-grid puzzles (killer sudoku, jigsaw sudoku, and others). The overlapping family links several 9x9 grids through shared boxes; the rule-changed family alters the constraints on a single grid.

What is overlapping sudoku?

Overlapping sudoku is any variant where two or more 9x9 grids share some of their cells, usually whole 3x3 boxes. The shared cells must be valid in every grid they belong to, which connects the grids into one puzzle. Samurai sudoku is the best-known example.

What is butterfly sudoku?

Butterfly sudoku overlaps four 9x9 grids in a 2×2 arrangement, sharing boxes where they meet in the middle. It's more tightly interlocked than samurai sudoku, so cross-grid deductions happen more frequently. The name refers to its wing-like symmetry.

What is gattai sudoku?

"Gattai" is Japanese for "combined" and refers to multi-grid sudoku puzzles. Gattai-5 is another name for the standard five-grid samurai sudoku, while larger gattai puzzles (super samurai) join six, eight, or more overlapping grids.

What is multi sudoku?

Multi sudoku is the general term for any sudoku puzzle built from more than one overlapping grid — including twin, samurai, butterfly, and gattai layouts. They all share the same solving approach: work one grid at a time and pass digits between grids through the shared cells.