Slitherlink Online Free
Join the dots into a single loop. Each number tells you how many of the four sides around it are part of the loop.
Drag from dot to dot to draw the loop. Tap a gap to draw a line, tap again for an ×, again to clear.
What is Slitherlink?
Slitherlink is a loop puzzle played on a grid of dots. You join neighbouring dots with lines to make one closed loop that never crosses or branches, and every number in the grid tells you how many of the four sides of its square the loop uses. A 0 means the loop goes nowhere near that square; a 3 means it wraps around three sides.
The puzzle was first published by Nikoli in 1989 and is also called Loop the Loop, Fences or Takegaki. It needs no arithmetic beyond counting to 3, but the best puzzles are long chains of logic. If you enjoy it, try Masyu, another loop puzzle, or Hashi.
How to play Slitherlink
- Draw lines between neighbouring dots, across or down, to make one closed loop. It can’t cross itself, branch or have loose ends.
- A number in a square says exactly how many of that square’s four sides are part of the loop. Squares without a number can have any amount.
- Mark the gaps you know are empty with an ×. Crosses don’t count for anything; they just help you keep track.
- Drag from dot to dot to draw lines, and drag over them again to erase. Tap a gap once for a line, twice for an × and a third time to clear it.
- Every puzzle is made fresh and checked to have exactly one solution, so it can always be solved by logic without guessing. Use Hint if you’re stuck, and pick a size at the top of the board.
Slitherlink skills
- Logical deduction
- Counting sides around a square
- Spotting patterns such as 3s and 0s
Level: Ages 9 and up
Tips for Slitherlink
Start with the 0s: put an × on all four sides. Then look at the numbers next to them.
A 3 in a corner of the grid always uses its two outer sides. Two 3s side by side always use the line between them and the two lines on either side.
Every dot has either no lines or exactly two. If a dot already has two crosses, its other two sides must be both lines or both empty.
The loop is one piece, so it can never close early. If a line would finish a small loop while other lines are still loose, that line must be empty.
Slitherlink questions and answers
How do you play Slitherlink?
Join the dots with lines to make one closed loop. Each number shows how many of the four sides around it belong to the loop, and the loop can’t cross itself or branch.
What do the 0 and 3 clues mean?
A 0 means none of the four sides around that square is part of the loop, so all four are crosses. A 3 means three sides are used and only one is empty, which makes 3s the best places to start.
Is Slitherlink the same as Loop the Loop?
Yes. Slitherlink is Nikoli’s name for the puzzle. It’s also published as Loop the Loop, Fences, Dotty Dilemma and Takegaki, with the same rules.
Does every Slitherlink puzzle have one solution?
Yes. Every puzzle here is checked by a solver when it’s made, so exactly one loop fits all the numbers and you never need to guess.
Which size should I start with?
Start with 5 × 5. It keeps extra numbers to give you more places to begin. 7 × 7 and 9 × 9 have fewer clues and need longer chains of reasoning.