Slitherlink vs Numberlink vs Train Tracks
All three puzzles ask the solver to draw a line. That is where the similarity ends. Slitherlink forms one closed loop on a dot lattice. Numberlink connects matching pairs with non-crossing paths. Train Tracks lays a continuous rail from a fixed entry to a fixed exit. Each puzzle produces a visually distinct first page, sells to a different search expectation, and belongs in its own listing.
Three line puzzles, three first pages
A buyer browsing Look Inside should know within seconds which pencil job the book is selling. A loop on dots looks nothing like pair-paths on an empty grid, and neither looks like a track board with counts printed along the edges. If the first page does not make the distinction obvious, the listing is selling the word “logic” instead of a specific puzzle.
Slitherlink — one closed loop on dots
Slitherlink prints a lattice of dots. Some faces carry a small digit that counts how many of that face’s edges belong to the loop. The solver draws exactly one closed loop along the grid edges, satisfying every clue.
The first page is dots and small digits — no filled cells, no grid of numbers. The answer key is the same lattice with the loop drawn in a heavier stroke. Keep the dots dark in print; if they fade, the book becomes unpleasant to solve.
Eighteen grid topologies are available, from standard rectangular to hexagonal, Cairo, Penrose, Hats, and Spectres. The first listing is still one closed loop on dots. Exotic lattice shapes are a visual differentiator for a second title, not a reason to split the product page into eighteen.
Editions: Lite covers the rectangular grid. Creative unlocks all eighteen topologies. Productivity adds batch generation and Customer JSON export.
Numberlink — matching pairs connected by paths
Numberlink scatters matching endpoint pairs on an otherwise empty grid. The solver connects each pair with a path. Paths run horizontally and vertically, never cross, and together fill every cell.
The first page is paired markers surrounded by empty space. The solved page is the opposite: winding lines filling the board. That contrast makes the answer-key section a second visual showcase, not an afterthought.
Endpoints default to numbers, but letters, colour shapes, or images are available. Changing the endpoint content changes the thumbnail without changing the mechanic. Arukone and Flow are alternate names for the same puzzle — they do not warrant separate shop listings.
Two solution rules are available. Strict requires a unique logical solution and supports boards up to 8×8. Flow accepts any valid path coverage and supports boards up to 15×15. The listing should state which rule the book uses, because a large Flow grid sold under a “unique logic” title misleads the buyer.
Editions: Creative and Productivity. Productivity adds Customer JSON, Interactive PDF, and Puzzle Slides export.
Train Tracks — one track from the counts
Train Tracks lays one continuous track from a fixed entry in the left column to a fixed exit in the bottom row. Numbers beside each row and column say how many cells in that line carry track. A few tiles are pre-printed as givens. Entry and exit meet the frame — there are no arrow glyphs.
By default, every generated board is guess-free with a unique solution. That is a back-cover claim worth printing. An optional Allow Guessing mode keeps uniqueness but relaxes the deduction requirement, producing harder boards where solving may need a what-if step. If a title uses that mode, the listing should say so.
Rails is the European name. It is not a separate product.
Custom tile art is straightforward: supply a straight and a curve image, and the engine rotates them into all six track-piece orientations. The default drawn tiles work well for a clean, classic look.
Editions: Creative covers static image output. Productivity adds Customer JSON export. Puzzle Slides and interactive HTML are available at higher tiers. Grid sizes range from 4×4 to 15×15 across five difficulty levels (Easy, Medium, Hard, Expert, Extreme).
What Look Inside has to prove
| Slitherlink | Numberlink | Train Tracks | |
|---|---|---|---|
| Puzzle page | Dot lattice with small clue digits | Matched endpoint pairs on an empty grid | Grid with row/column counts, entry/exit markers, and given tiles |
| Answer key | The closed loop drawn on the lattice | Paths connecting every pair, filling the board | The completed track from entry to exit |
| The pencil job | Draw one closed loop along edges | Connect each pair without crossing paths | Lay continuous track satisfying every count |
| Grid topologies | 18 (rectangular through Spectres) | Rectangular only | Square only (4–15) |
| Content options | Digits on faces (fixed) | Numbers, letters, colour shapes, or images | Track tiles (default or custom art) |
Every answer key in this group is a drawing, not a digit fill. Drawn answers need visual weight and dedicated pages. A 100-puzzle interior carries a proper solutions section, not four grids shrunk into a corner. The conventions for puzzle book answer keys apply here.
One mechanic per title
A book that opens on a closed loop and later switches to pair-paths is two products bound together. Each line puzzle reads differently enough that a buyer who wanted Slitherlink will feel misled by a Numberlink section halfway through.
A mixed logic book is a legitimate product, but only when the title says so — mixed puzzle books covers that composition. The default that sells on the logic shelf is one mechanic, consistently executed, with a Look Inside that proves which one.
Nearby puzzles that do not belong here
Galaxies, Shikaku, and Queens split a grid or place pieces. Their first pages are dots, numbered rectangles, or empty regions — not a drawn line. Country Tour is a region-traversal loop and not a Numberlink variant. Mazes are a different family entirely. If you have not yet chosen a puzzle family, which puzzle type fits your audience is a wider starting point.
Pick the line, publish the title
Slitherlink is a closed loop on dots. Numberlink is paths between matching pairs. Train Tracks is a rail completed from row and column counts. Three distinct first pages, three distinct listings. Pick the one your audience is searching for and let Look Inside prove which pencil job they are buying.