Slitherlink (also called Fences, Loop the Loop, or Takegaki) is a logic puzzle published by Nikoli. You draw a single closed loop on a grid of dots. Some cells contain a number (0–3) that tells you exactly how many of that cell's four edges are used by the loop.

How do I play Slitherlink?

Click or tap between two adjacent dots to toggle an edge on or off. You can also mark edges with an X to indicate they are definitely not part of the loop. The goal is to form a single closed loop with no branches that satisfies every number clue.

What is the best strategy for Slitherlink?

Start with 0-cells (no edges around them — mark all four as X) and 3-cells adjacent to 0-cells (three edges forced). Look for corners and edges of the grid where constraints are tighter. Use the rule that each dot must have exactly 0 or 2 loop edges.

Can Slitherlink puzzles be solved without guessing?

Yes. Every puzzle on this site has a unique solution reachable through pure logical deduction — no guessing or trial-and-error is needed.

What grid sizes are available?

This version offers 5×5, 7×7, and 10×10 grids, each with Easy, Medium, and Hard difficulty levels that vary the number of clue cells and constraint tightness.

Play Slitherlink (Fences) Online

Draw a single closed loop on a grid of dots. Numbers inside cells tell you exactly how many of that cell’s four edges are part of the loop.

Time

0:00

Edges

0 / 0

Wins

Click between dots to draw the loop

What Is Slitherlink?

Slitherlink (also known as Fences, Loop the Loop, or Takegaki) is a logic puzzle first published by Nikoli in 1989. It has since become one of the most popular loop-drawing puzzles in the world, appearing in puzzle books, newspapers, and apps.

The puzzle takes place on a rectangular grid of dots. Some of the cells between the dots contain numbers from 0 to 3. Your goal is to connect the dots with horizontal and vertical lines to form a single closed loop — no branches, no crossings — that satisfies every number clue.

Rules

Draw horizontal and vertical edges between adjacent dots.
The edges must form a single closed loop — no branches, no loose ends.
A cell containing a number 0, 1, 2, or 3 must have exactly that many of its four edges drawn.
Cells without a number may have any number of edges (0–4).
Every dot touched by the loop must have exactly 2 edges meeting at it.

How to Play

Edge Mode (default): Click between two adjacent dots to draw or remove a loop edge.
X Mode: Toggle to X mode, then click to place an “X” on an edge to mark it as definitely not part of the loop. This is a helpful note-taking tool.
Watch the clue numbers — they turn green when satisfied and red when they have too many edges.
Use Check to validate your solution or New for a fresh puzzle.

Strategy Tips

1. Start with 0-Cells

A 0-cell means none of its four edges are part of the loop. Mark all four edges with an X immediately. This often cascades into neighbouring cells, especially if they contain a 3.

2. The 3-Next-to-0 Rule

If a 3-cell is adjacent to a 0-cell, their shared edge is forced off. That means the 3-cell’s other three edges are all part of the loop. This is one of the most powerful opening moves.

3. Diagonal 3-3 Pattern

Two 3-cells that are diagonally adjacent force a specific zig-zag pattern. The shared corner must have exactly 2 edges, and the outer edges of both 3-cells are all drawn.

4. Corner and Border Cells

Cells at corners of the grid only have 2 – 3 possible edges (the grid boundary blocks the others). A 2 in a corner forces both available edges. A 3 on an edge with 3 available edges forces all of them.

5. The Parity Rule

Every dot on the loop has exactly 2 edges. If a dot already has 1 edge, it must have exactly 1 more. If a dot has 0 edges but only 2 possible remaining edges, either both are drawn or neither is — use this to chain deductions.

6. Prevent Small Loops

The loop must be one single closed path. If drawing an edge would close a small loop that doesn’t include all drawn edges, that edge must not be drawn. Always watch for premature closures.

Slitherlink vs Other Puzzles

vs Masyu: Both are loop-drawing puzzles, but Masyu uses black and white circles with turning rules, while Slitherlink uses numbered cells counting edges.
vs Hashi: Hashi connects islands with bridges to form a network; Slitherlink draws a single closed loop.
vs Nonograms: Nonograms fill cells to reveal pictures; Slitherlink draws edges to form a path. Both use number clues for deduction.
vs Sudoku: Both are pure logic, but Sudoku places numbers while Slitherlink draws a geometric loop.

Frequently Asked Questions

A logic puzzle where you draw a single closed loop on a grid of dots. Numbers in cells tell you how many of that cell’s edges are part of the loop. Also known as Fences or Loop the Loop.

In Edge Mode, click between two adjacent dots to toggle that edge on or off. Switch to X Mode to mark edges as definitely excluded — useful for note-taking while solving.

Start by marking all edges around 0-cells with X. Then look for 3-cells next to 0-cells — three of their edges are forced. Work outward from these certain deductions.

Yes. Every puzzle here has exactly one solution reachable by pure logical deduction.

5×5, 7×7, and 10×10, each with Easy, Medium, and Hard difficulty levels.

More Puzzle & Strategy Games

If you enjoy Slitherlink, try these other free games on our site:

Masyu

Draw a single loop through circles on a grid — another classic Nikoli loop puzzle.

Hashi

Connect numbered islands with bridges to form one connected network.