How to Play Slitherlink

➰What is Slitherlink?

Slitherlink gives you a lattice of dots with numbers scattered in the cells. Your job: draw one single closed loop along the grid lines. Each number tells you exactly how many of that cell's four edges belong to the loop — a 3 is hugged by the loop on three sides, a 0 is touched on none. The finished loop never branches, never crosses itself, and is the only loop on the board.

📜The rules

1. The loop runs along cell edges between the dots — never diagonally.
2. A numbered cell must have exactly that many of its four edges drawn. Unnumbered cells may have any number of loop edges (0–3; 4 would be an isolated ring, which can't happen in a valid single loop).
3. At every dot, the loop either doesn't touch, or passes through using exactly two edges. Three or four edges at one dot is a branch — illegal.
4. The result is exactly one loop. Two separate loops, even if every number is satisfied, is not a solution.
5. On DailyGrid: tap an edge to draw it, tap again for an X (known-empty edge), tap again to clear.

🎯Strategy

Getting started — forced patterns

• 0s: cross out all four edges. This also limits every neighboring cell.
• 3 in a corner: both outer (border) edges are IN — the loop runs along the border on both sides of the cell. That also satisfies two edges at the corner dot, so every other edge at that dot is OUT.
• 1 in a corner: both outer (border) edges are OUT.
• Adjacent 3s (sharing an edge): the edges on both outer sides of the pair are IN, and the shared-edge's parallel lines form a forced corridor — one of the most powerful starts in the game.
• Diagonal 3s (touching at a dot): the two edges at the shared dot, on the far side of each 3, are forced IN.

Level up

• Dot accounting: if a dot already has two loop edges, X the other two. If it has one loop edge and two Xs, the last edge is forced IN.
• Never close a small loop early. If drawing an edge would complete a little loop while numbers elsewhere are unsatisfied, that edge is OUT — the final loop must be the only one.
• 2s on the border force a step inward: the loop must dive into the grid and come back, giving you a chain of forced edges along the edge.
• Coloring (advanced): mentally shade inside/outside. Every loop edge separates inside from outside; propagating the two colors across known non-edges cracks large puzzles fast.

Pro tips

• Keep Xs as up to date as edges — in Slitherlink, an X is information, not the absence of it.
• When a numbered cell has all its edges decided except one and still needs count, that last edge is forced. Sweep for "one edge left" cells after every move.

⚠️Common mistakes

• Drawing a branch at a dot (3 edges) — always count the dot, not just the cells.
• Closing a small loop in a corner to satisfy a 2 or 3, orphaning the rest of the grid.
• Guessing instead of marking Xs. Most "stuck" Slitherlinks are actually solved by one more round of dot accounting.

❓FAQ

What are the rules of Slitherlink?

Draw one closed loop along the edges; every numbered cell has exactly that many loop edges; no branches, no crossings, no second loop.

What are the best starting patterns?

0s (all edges out), corner 3s and 1s, and adjacent or diagonal 3 pairs. They're detailed in the strategy section.

Is the DailyGrid Slitherlink free?

Yes — a new Slitherlink every day at midnight ET, no account needed — the daily puzzles are free. Always. One of ten daily puzzles on DailyGrid.

Where can I learn the other games?

See all ten DailyGrid guides.