Zigmark is a loop-drawing logic puzzle. You draw one closed loop through every marked dot on a grid: circles must be passed straight through, triangles must be turned at.

Does every board have one solution?

Yes. Every Zigmark board is generated from a real loop and verified by a solver before it ships, so exactly one loop fits the marks.

Can the loop pass through an unmarked dot?

No. The loop passes through marked dots only, which is what makes the marks meaningful.

How many lines meet at each dot?

Exactly two. A dot is either skipped entirely or passed through with two connections, so the loop never branches or ends.

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LOGIC · HOW TO PLAY

How to play Zigmark

One closed loop runs through a grid of dots. Circles mean it goes straight. Triangles mean it turns. Nothing else is on the board.

The rules

Draw a single closed loop along the lines that join neighbouring dots.
The loop passes through every marked dot and no unmarked dot.
○ — the loop passes straight through the dot.
△ — the loop turns at the dot.
Every dot on the loop has exactly two connections. The loop never branches, never crosses itself and never touches itself at a point.

First moves

Start with the triangles. A circle has only one way through — straight — so it gives you a line but no decision. A triangle has four possible ways to turn, which is where the information is. Every triangle you resolve narrows the loops around it.

Then close the isolated runs. If two triangles sit in a corner with straight circles along both sides, the only way to pass through all of them is to bend inward. Corners solve themselves once you look at them.

Count the lines at each dot. Every marked dot needs exactly two. When a dot already has two, every other direction from it is dead — and that often kills a candidate direction a few dots away.

The turn trap

The most common way to lose a Zigmark board is to bend in the wrong direction at a triangle and only notice ten dots later. The loop cannot cross itself, so a wrong turn usually creates a shape that has to close on the wrong side of an existing line.

When that happens, do not start over. Look at the last triangle where you had two plausible directions and take the other one — the loop is a single chain, so the mistake is always at the most recent real choice, not at the end.

Why the board is fair

Boards are not filtered from random scribbles. Each one starts as a real loop that is grown on the grid, then the marks are stripped out one at a time while a solver confirms exactly one loop still fits. What ships is the smallest set of marks that still has one answer.

So if you are stuck, the board is not ambiguous — you have not yet used one of the marks that is doing real work.

Where it sits next to other puzzle games

Loop puzzles usually ask you to satisfy a number of surrounding lines, or to thread beads with turn rules. Zigmark removes the numbers and keeps only the shape of the path: every dot is a decision point, and the loop has to be consistent across all of them at once.

If you like pure deduction without arithmetic, try Ripple next — same promise of one solution and no guessing, but built from distances instead of lines.

Frequently asked

Is Zigmark like Slitherlink?

Both draw a single loop, but Slitherlink counts edges around numbered cells. Zigmark has no cells and no numbers — the constraint is turn or straight at dots.

Do I need to fill every dot?

No. Only marked dots are on the loop. Unmarked dots are skipped entirely, and that is often the hardest part to see.

Is guessing ever needed?

No. Every board is verified to have exactly one loop, and the marks are chosen so the loop can be reached by deduction.

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