The Complete Rules

You are given a cluster of hexagons and a pool of numbers. Place one number in every hexagon so that no connection between two hexagons breaks a rule. When every hexagon is filled and not a single connection is broken, the puzzle is solved.

Shestoku takes its name from shest — “six” — and the -ku of sudoku: a number puzzle built on the six sides of a hexagon.

01 The pieces

Hexagons

The board is a cluster of hexagons. Each one holds exactly one number, and every hexagon must be filled for the puzzle to count as complete. The number in the top-right corner tells you how many hexagons there are to fill — the size of the challenge in front of you, and the count of numbers you will place.

The number pool

Beside the board is a pool of numbers — exactly as many numbers as there are hexagons. Each number is used once and only once. When the board is full, every number from the pool has been placed and no number repeats.

The pool is optional. It is hidden by default and can be revealed with a button whenever you want it. Shown, it is a handy reference and lets you drag numbers onto the board. Hidden, you simply type the numbers in — useful if you would rather solve without the list in front of you.

02 Connections

Two hexagons are connected in either of two ways:

Touching — they share an edge, sitting directly against each other.
Connector lines — a drawn line joins two hexagons that may not be touching.

Both kinds of connection count equally. If two hexagons are connected — whether by touching or by a line — the rules apply between them. If they are not connected, nothing restricts them, even if they sit near each other on the board.

03 The two rules

Two connected hexagons may never hold numbers that break either of these:

Rule one

No consecutive numbers

Connected hexagons cannot hold numbers that sit next to each other on the number line.

7 ✕ 840 ✕ 41

Rule two

No shared digits

Connected hexagons cannot hold numbers that share any digit.

31 ✕ 135 ✕ 57

A connection is legal only if it passes both rules. The numbers must be non-consecutive and share no digit.

04 Legal or not?

Connected pair	Allowed?	Why
7 and 8	✕ No	Consecutive on the number line
31 and 13	✕ No	Share the digits 1 and 3
5 and 57	✕ No	Both contain a 5
7 and 20	✓ Yes	Not consecutive, no shared digit
48 and 13	✓ Yes	Not consecutive, no shared digit

05 How to play, step by step

Pick a hexagon. Click it to focus it.

Place a number. Type the number on your keyboard, or — if the pool is shown — drag one over from it. Backspace clears the hexagon.

Work the connections. As you place numbers, keep each one clear of its connected neighbors — no consecutive values, no shared digits.

Fill the whole board. The puzzle gives no hints while you work. The board stays plain until every hexagon holds a number.

Check your answer. The moment the board is full, it is judged. If everything is legal, the board switches to its solved state — you have won. If something is wrong, the hexagons in conflict are marked so you can find and fix them.

06 A note on solving

Because feedback only arrives when the board is full, the challenge is to reason ahead rather than guess and check. Start with the most connected hexagons — the ones with the most neighbors are the hardest to satisfy, so settling them early narrows everything else. Every puzzle you are given has at least one valid solution; it was verified solvable before it ever reached you.

Every puzzle is solvable. The only question is whether you can find the way.

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