Yajilin Puzzles
Shade cells to satisfy every arrow clue, then draw one closed loop through everything that stays white. The loop never touches itself, and every deduction along the way is explained — including why each wrong shading breaks the rules. Sixty grids from 7×7 to 9×9, generated fresh every time.
Also known as Yajirin and the arrow clue loop puzzle, from the Nikoli family alongside Slitherlink.
Two Rules That Fight Each Other
A Yajilin puzzle asks for two things at once. The clues want specific cells shaded: each number counts the shaded cells on its arrow's line. The loop wants everything else: every cell that stays white must sit on one closed loop with exactly two white neighbours. Shading a cell serves the clues and starves the loop — the whole puzzle lives in that tension.
How To Solve A Yajilin Grid
- Start with satisfied clues. A clue whose shaded count already matches its number turns every undecided cell on its line white.
- Then finish the hungry ones. A clue that still needs shaded cells takes them from its own line — undecided cells there turn black.
- Apply the degree rule. A white cell ends with exactly two white neighbours: two white neighbours force its other neighbours black.
- Watch the corners. Two white cells diagonal to each other, with both shared neighbours black, make the loop touch itself — one of those shared neighbours must go white.
- Close the loop last. When every white cell has exactly two white neighbours and they all connect, the grid is solved.
The clues are half the rules, not all of them. Grids where every clue is satisfied can still fail on the loop: a white cell with three white neighbours, or a corner touch, breaks the puzzle with every clue exact. Solve the clues, then audit the loop.
The Four Board Sizes
| Family | Board | What changes |
|---|---|---|
| 7×7 | The classic square | Short arrow lines; the place to learn clue closure |
| 7×9 | Wide grids | Longer lines make every count matter more |
| 8×8 | Balanced middle | Long loops with sparse guidance |
| 9×9 | The full board | The deepest clue chains and the hardest closures |
Why Yajilin Trains Both Skills
Most loop puzzles hand you the constraints up front; most shading puzzles have no loop at all. Yajilin makes the two fight: the clues push shading one way, the loop's degree and corner rules push back, and the answer is the single grid that satisfies both. That is why it sits beside Slitherlink in the loop family — the same loop discipline, plus a shading battle the loop keeps winning until you get the clues right.
Yajilin Puzzles: Frequently Asked Questions
What are the rules of Yajilin?
Shade some cells black, then draw a single closed loop through the centres of all the remaining white cells, moving horizontally or vertically. The loop never touches itself, not even at a corner. Clue cells carry a number and an arrow: the number counts the shaded cells on the straight line the arrow points down. Clue cells are never shaded and never sit on the loop.
How do you solve a Yajilin puzzle?
Start with satisfied clues — they turn their undecided line cells white. Hungry clues shade their undecided line cells. Then apply the degree rule: a white cell with two white neighbours forces its other neighbours black. Close the loop last.
What does the number and arrow mean in Yajilin?
The number counts shaded cells on the straight line running from the clue cell in the arrow's direction, up to the grid edge. The clue cell itself is never counted and never shaded.
Can shaded cells touch each other in Yajilin?
Yes — shaded cells may share an edge. The limit comes from the loop: two white cells diagonal to each other with both shared neighbours black would make the loop touch itself at a corner, and that is forbidden.
Why is my loop wrong when every clue is satisfied?
The clues are half the rules. The white cells must form one single closed loop — every white cell needs exactly two white neighbours, no branches, no corner touches. Audit white cells with three white neighbours first.
How many puzzles are there?
There is no fixed number. Each grid is rebuilt from the short seed in the page address, so the supply is effectively unlimited. Copying the grid link saves that exact grid permanently.
Can I practise one pattern at a time?
Yes. Pick any pattern from the catalogue above and the board switches to that grid size and difficulty only, with its own address you can bookmark or hand out.
Is Yajilin harder than Slitherlink?
Generally yes — Yajilin mixes shading decisions with the loop. Start with the 7×7 grids here before the 9×9 boards, and keep Slitherlink as the warm-up.