Logic puzzle · Single loopSlitherlink,
Slitherlink,
one closed loop.
Draw a single closed loop on the grid edges so every number is touched by exactly that many segments.
- Segments
- 0
- Time
- 0:00
- Hints
- 0
About the gameHow Slitherlink works,
How Slitherlink works,
in short.
- Step 01
Clues count edges.
Each number tells you how many of its four surrounding edges belong to the loop. Blanks are free.
- Step 02
Click edges on or off.
Tap an edge to cycle it empty → drawn → ✕. The ✕ is your own mark for an edge you've ruled off the loop. Use the clues to deduce one edge at a time.
- Step 03
One single closed loop.
Every clue satisfied, every edge either on or off, and the on-edges form one continuous loop.
Questions
Slitherlink questions, answered.
Slitherlink is a deduction puzzle by Nikoli — the same publisher that gave the world Sudoku. The board is a grid of cells, some of which carry numbers from 0 to 3. The goal is to draw a single closed loop on the grid edges so that each numbered cell is touched by exactly that many segments of the loop. There is one solution, but plenty of paths to find it.
Click an edge between two grid dots to cycle it through three states: empty, drawn as part of the loop, or marked with an ✕ to remember it cannot be on the loop. The puzzle is solved when every clue cell is satisfied and the drawn edges form a single closed loop with no crossings, branches, or strays.
The loop runs along edges between adjacent dots — horizontally or vertically, never diagonally. The loop must be a single closed curve with no branches and no disconnected pieces. A cell labelled 0 has no loop segments on its four edges; a cell labelled 3 has exactly three; and so on. Cells without a number have no constraint.
Easy is a 5×5 board with most cells labelled — a gentle introduction. Medium is 7×7 with roughly 70% of cells clued; Hard is 9×9 with around 55% clued. Fewer clues means more deduction work per move.
Start with 0s and 3s — they tend to force moves. Two adjacent 3s force three edges on the boundary between them and one each on the far sides. A 0 next to a 3 immediately tells you three of the 3's edges. Diagonally touching 3s force the four outer corners as edges. When a cell has too few free edges, every remaining edge must be on; when it has too few used edges, every remaining one must be off.
Yes. A fresh random puzzle is generated each time you change difficulty or hit "New puzzle". There is no daily limit and no streak counter — solve as many as you like.
Each puzzle is built by reverse construction: a random simply-connected blob of cells is grown inside the board, and its boundary is the canonical loop. The clue numbers are the per-cell counts of boundary edges. A fraction of clues is then hidden according to the difficulty.
Yes. Tap an edge to cycle it through empty, drawn, and ✕. Larger boards work best on a tablet or laptop — the 5×5 easy size is comfortable on a phone.
Each edge cycles through three states — empty, drawn, ✕ — so a third click returns it to empty. To wipe everything and start fresh on the same puzzle, hit Reset on the toolbar.
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