Puzzle guide

How to solve Yajilin

Yajilin mixes two puzzles in one: you shade a few cells, and you draw one loop through all the others. Arrows with numbers tell you how many shaded cells lie in their direction. The two halves help each other, and that is what makes it fun.

Play Sagitta now All about Yajilin

The rules

Shade some cells, and draw one closed loop through every other cell, except the arrows. The loop runs from cell centre to cell centre, across and down, and never branches or crosses itself.
Two shaded cells never sit side by side; corners may touch.
An arrow says how many shaded cells lie in its direction, all the way to the edge.
An arrow's own cell is neither shaded nor on the loop.

A solved puzzle

A solved puzzle. The top arrow sees one shaded cell to its right, the middle arrow one above it, and the loop passes through every other cell.

Your first moves

Find every 0 arrow: every cell in its direction is on the loop.
Find arrows that need as many shaded cells as their line can hold. Shaded cells can't touch, so they have to alternate.
Around every shaded cell, the four neighbours are on the loop. Mark them with a dot.
Look at corners and at cells next to arrows: a cell with only one way in or out cannot be on the loop, so it is shaded.

Techniques, step by step

A 0 arrow

An arrow with 0 sees no shaded cell in its direction, all the way to the edge. So every cell in that line is on the loop. Mark them all with a dot. Those dots soon tell you where the loop has to go.

Nothing is shaded to the right of a 0: every cell there is on the loop.

As many as fit

This arrow needs 2 shaded cells in a line of three. Shaded cells may not touch, so two of them in three cells can only sit at both ends, with a loop cell between them. Whenever an arrow asks for as many shaded cells as its line can hold, they alternate: shaded, loop, shaded.

Two shaded cells in three: both ends.

Beside a shaded cell

Two shaded cells never touch side by side. Every cell has to be shaded or on the loop, so each neighbour of a shaded cell is on the loop. Mark them with dots. This is the move you make most often, and it hands the loop part of the puzzle lots of cells.

The four neighbours of a shaded cell are on the loop.

A cell with no way through

A loop cell needs two neighbours to come in and go out. The corner cell here has an arrow next to it, and an arrow cell is never on the loop. So the corner has only one way out, and it cannot be on the loop. It must be shaded. And indeed, the arrow next to it says 1 to the left. Look for these stranded cells in corners and along edges.

Only one way out: the corner cell is shaded.

Follow the loop

Every cell that is not shaded and not an arrow is part of the same loop, and the loop goes in and out of each one exactly once. A cell with only two possible directions left must use both. Draw those lines, and put an X on the borders the loop cannot cross. The loop part often fixes cells the arrows could not.

Do not close the loop too early

There is only one loop. If joining two line ends would close a small loop while dots or lines are still outside it, that step is wrong: put an X on it. On bigger boards, this rule often tells you which of two cells must be shaded.

Common mistakes

Counting only the next cell. An arrow counts every shaded cell in its direction, all the way to the edge of the board.
Shaded cells side by side. Corners may touch, sides never.
A loop through an arrow. Arrow cells are neither shaded nor part of the loop.
Leaving cells out. Every cell that is not shaded and not an arrow must be on the loop. A cell the loop cannot reach must be shaded.

Questions and answers

What is Yajilin?

A Japanese logic puzzle where you shade some cells and draw one closed loop through all the others. Arrows with numbers say how many shaded cells lie in their direction. It is also published as Arrow Ring.

Do arrows count only the cells next to them?

No. An arrow counts every shaded cell in its direction, all the way to the edge of the board.

How do I shade a cell or draw the loop?

Tap a cell's middle to shade it, again to mark it for the loop with a dot, and again to clear it. Drag across cells to draw the loop, and tap between two cells to cross that step out.

Does every cell have to be used?

Yes. Every cell is shaded, an arrow, or on the loop. No cell is left over.

Where should I start?

With 0 arrows and arrows that need as many shaded cells as their line can hold. Then put dots around every shaded cell and look for corner cells with only one way out.

Ready to play?

Read the arrows, dot the neighbours of every shaded cell, shade the cells the loop cannot reach and keep it one loop. That is how Yajilin's two halves come together.