Slitherlink are addictive loop-forming puzzles which were invented in Japan. Using pure logic and requiring no math to solve, these fascinating puzzles offer endless fun and intellectual entertainment to puzzle fans of all skills and ages.

Each puzzle consists of a rectangular lattice of dots with some clues in various places. The object is to connect the dots surrounding each clue so that the number of lines equals the value of the clue and the lines around all clues form one continuous loop with no crossings or branches. Empty squares may be surrounded by any number of lines.

The game features 2-finger tapping for quick zoom, auto complete clues setting and a link segment highlighting option to help to avoid creating separate loops.

For more fun, Conceptis Slitherlink includes a Weekly Bonus section providing an extra free puzzle each week.


• 90 free Classic Slitherlink puzzle samples
• 30 extra-large puzzles bonus for iPad only
• Extra bonus puzzle published free each week
• Multiple difficulty levels from very easy to extremely hard
• Puzzle library continuously updates with new content
• Manually selected, top quality puzzles
• Unique solution for each puzzle
• Hours of intellectual challenge and fun
• Sharpens logic and improves cognitive skills


• Concurrently playing and saving multiple puzzles
• Puzzle library sorting and hiding options
• Unlimited Undo and Redo
• Auto complete clues
• Highlight link segment
• Quick zoom using 2-finger tap
• Check puzzle
• Track puzzle solving times


Slitherlink have also become popular under other names such as Fences, Loop the Loop, Loopy, Suriza, Dotty Dilemma and Number Line. Similar to Sudoku, Kakuro and Hashi, the puzzles are solved using logic alone. All puzzles in this app are produced by Conceptis Ltd. - the leading supplier of logic puzzles to printed and electronic gaming media all over the world. On average, more than 20 million Conceptis puzzles are solved each day in newspapers, magazines, books and online as well as on smartphones and tablets across the world.

What’s New

Version 3.6

Optimized for iPhone XS Max, iPhone XR and iOS 12

Ratings and Reviews

4.8 out of 5
106 Ratings

106 Ratings

MichelleC333 ,

Great fun, offers SO many different puzzles

This app is great fun, thought-provoking and offers SO much variety of different puzzles at various difficulty and sizes. You’ll need to read the Help Menu to learn how to play. You’ll want to read (I highly recommend reading) the Techniques section as well, it’s a lifesaver. I even wrote them down to use as a reference until I knew them by heart. I am a Conceptis Puzzles fan and this is one of my favorites.

Illusyn ,

Requires logical thinking

Like all Conceptis puzzles Slitherlink is cleanly and robustly implemented. There is a significant help section with well thought out explanations. Each puzzle has a unique solution and CAN be solved by reasoning. I have been playing Slitherlink for months (I do the “very hard” puzzles) and the puzzles continue to be challenging. To my taste Slitherlink is the best in the Conceptis collection.

LovelyLaughter ,

Surprisingly addicting

I came across the puzzle in a sudoku book and I’m hooked. This is so simple yet so difficult (even the super easy ones!) I’m glad I could find a new puzzle to challenge myself with. The app does a wonderful job of playability. I’m not even sure they could make it better.


Conceptis Ltd.
16.3 MB

Requires iOS 8.0 or later. Compatible with iPhone, iPad, and iPod touch.


English, Japanese, Simplified Chinese

Age Rating
Rated 4+
© Conceptis Ltd.
In-App Purchases
  1. Easy Variety 1 $1.99
  2. Medium Variety 1 $1.99
  3. Hard Variety 1 $1.99


  • Family Sharing

    With Family Sharing set up, up to six family members can use this app.

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