➰ Slitherlink
🧩 Logic · 0 playsSlitherlink
Draw one closed loop so that every numbered cell is touched by exactly that many walls.
About Slitherlink
A lattice of dots carries scattered numbers, and the task is to draw a single closed loop along the edges so that each number counts precisely the loop segments surrounding its cell. A three is nearly encircled, a zero is untouched, and the loop must neither branch nor cross itself nor break into separate rings. The pleasure of Slitherlink lies in its patterns: certain arrangements of clues — a three in a corner, two threes adjacent — force segments before anything else is known, and the loop then grows from those certainties. The checker points out exactly which rule a faulty loop has broken.
How to Play
Tap an edge between two dots to draw a wall there; tap again to remove it, or mark an edge as empty. Each numbered cell must end up with exactly that many walls around it. All the walls together must form one single closed loop, with no branches and no crossings.
💡 Tips & Strategy
Learn the forced patterns and half of every puzzle draws itself. A 0 kills all four of its edges, and every edge killed beside a 3 forces the 3's remaining edges. A 3 in a corner always takes the two edges meeting at that corner. Two 3s side by side take the three parallel edges between and beside them, and two 3s diagonal to each other take their outer corners.
Think in terms of the dots as much as the cells. Every dot on the finished loop has exactly two line ends, and every dot off it has none — so a dot that already carries two lines has its other edges dead, and a dot with one line and two dead edges has its last edge forced. Marking dead edges with a cross is not bookkeeping; it is where most deductions actually come from.
Use the loop's own topology late in the solve. There is only one loop, so any move that would close a small ring while clues remain unsatisfied is wrong, however legal it looks locally. When two open ends approach each other, ask whether joining them finishes the puzzle; if it does not, they must be kept apart.
A subtler tool for hard grids: the loop crosses any closed boundary an even number of times. Around a single cell, along the grid's edge, around any region you care to draw — if an odd number of crossings would be forced, the position is wrong. This parity check settles cells that pattern knowledge cannot.