How to play Rail Tracks
The rules
The track enters the grid at A and leaves it at B. Both sit just outside the grid, next to the side of a border cell.
Lay one track from A to B. It runs through the centres of cells that share a side. In each cell it goes straight or turns a corner; it never branches and never crosses itself.
The number above each column and at the end of each row tells how many cells in that line hold track. Every track cell is part of the one track from A to B: no loops and no loose pieces. Some puzzles show a few fixed track pieces to start from.
Every puzzle has exactly one solution, and logic alone is enough to reach it. You never have to guess.
How to play here
- Lay track: drag from cell to cell. One drag is one move, so Undo takes back the whole stroke.
- Take track back while you drag: drag back over the cells you just passed.
- Remove track: drag along track that is already there, or tap a cell to clear its track.
- Mark a cell as empty: tap a cell with no track. An × appears; tap again to clear it.
- Keyboard: arrow keys to move, Shift+arrow to lay or remove track towards that side, X to mark a cell empty, Delete or Backspace to clear a cell’s track.
- Undo and redo: Ctrl+Z and Ctrl+Y (on a Mac: ⌘Z and ⌘⇧Z).
- Hint: each press of Hint tells you more: first where to look, then which technique works there, and finally which two cells to join. If there is a mistake on the board, the hint shows you where.
When a row or column holds exactly its number of track cells, its number turns green with a check. When it holds too many, or the cells you marked empty leave too few open cells, the number turns red with a wavy underline.
Difficulty levels
The level is set by the hardest technique the puzzle requires. Larger grids tend to need harder techniques:
| Level | Grid | Techniques required |
|---|---|---|
| Easy | 6×6 | Counting, Only way |
| Medium | 6×6 | + No loops |
| Hard | 7×7 | + Try it |
| Expert | 8×8 | + Try it, many times |
Techniques
Counting
If a row or column already has all its track cells, every other cell in it is empty. If it needs every cell that is still open, all of them hold track.
Only way
Every track cell has exactly two ends. If a track cell has only two ways out left, the track uses both. If it already has two, its other sides are closed. A cell that has fewer than two ways out can’t hold track at all.
No loops
Joining two cells that are already the two ends of the same piece of track would close a loop, so they stay apart. In the same way, the piece from A and the piece from B can only meet when the track is complete: if other track cells are still loose, or the track would be too short, they can’t join yet.
Try it
Suppose two neighbouring cells are joined and follow the easier techniques. If a cell then gets three ends, a count can’t be met, or the track closes a loop, they can’t be joined. The same works the other way round.
Tips
- Start with rows and columns whose number is 0 or equal to their length: they are decided at once.
- Look at A and B first: each starts the track in a known cell, and its neighbours often have only one way out.
- Mark empty cells with an ×. The open cells that are left show the ways the track can still go.
FAQ
- How do I play Rail Tracks?
- Lay one track from A to B through cells that share a side. The track goes straight or turns, never branches or crosses itself, and every row and column holds as many track cells as its number says.
- Is there a new puzzle every day?
- Yes. A new Rail Tracks puzzle is published every day at each of the four levels: easy, medium, hard and expert. Earlier puzzles are in the archive.
- Do I need an account to play?
- No. You play right in your browser, with no sign-up and no cookies. Your progress is saved in your browser.