Build one continuous railway from A to B with straight and curved rails, matching the track total for every row and column.
Train Track Logic asks you to finish a railway line across a grid. Two ends are marked, A and B, and a few rail pieces may already be laid. Numbers along the top count how many squares in each column hold track, and numbers down the right side do the same for each row. Your job is to fill in one route that agrees with every count.
It began life as Tracks, a puzzle James Harvey wrote for Simon Tatham’s collection.
The goal
The railway enters at A on the left edge and exits at B on the bottom edge. Between them, it can only use straight pieces and quarter-turn curves. It never crosses itself, never splits in two and never forms a closed circle. Each square either has no track or exactly one piece that links two of its sides.
Any rail printed on the board at the start is part of the answer, including the pieces in both entrance squares.
Laying rails and taking notes
There are two kinds of marks, and learning both makes the puzzle much easier.
- Rails go on edges. Left-click the border between two squares to join them with track. Right-click it to add a cross that means the line cannot pass there.
- Notes go inside squares. Left-click a square to say track runs through it, before you know which way. Right-click to mark it as empty.
- Drag across a run of squares to note a full line in one sweep.
If a line ends up holding more track than its number allows, that number goes red. On a keyboard, move with the arrows, press Enter to lay rails and Space for a cross. N, U and R handle new game, undo and redo.
Strategy notes
Begin with lines whose number is 0 or equal to their full length. Those are settled right away, one as all empty and the other as all track.
Next, extend the given pieces. Each printed rail points into a neighbor that must also carry the line. Remember that a track square uses exactly two of its four edges, so as soon as two edges are crossed out, the remaining pair is forced.
Once a row’s total is reached, fill its leftover squares with crosses so the grid stays easy to read. Watch out for any section that would bend back and close a ring, since a ring can never connect to both ends. Count turns too. If the line has to reach a distant column, it must bend toward it somewhere.
Good to know
Twelve presets run from 8x8 to 15x15, with Easy, Tricky and Hard levels, and you can also set a custom size. Tricky and Hard boards ask for longer chains of reasoning than the Easy ones.
Controls
| Action | Keyboard | Mouse | Touch |
|---|---|---|---|
| Lay a track piece across an edge | Arrow keys to move onto an edge, then Enter | Left-click the edge between two squares | Tap the edge with Tap set to Track |
| Mark an edge as "no track here" | Space on an edge | Right-click the edge | Press and hold the edge, or set Tap to Cross and tap |
| Mark a square as "has track" / "no track" | Enter / Space on a square | Left-click / right-click inside the square | Tap / press and hold inside the square |
| Mark a whole line of squares | — | Left- or right-drag across several squares | Drag (press and hold first for crosses) |
| New game, undo, redo | N, U, R | Menu buttons above the grid | Menu buttons above the grid |
Train Track Logic FAQ
Can I play Train Track Logic on a phone or Chromebook?
Yes. Mouse, keyboard and touch are all supported. On a touchscreen, tap an edge to lay rails and press and hold to place a cross, or flip the Tap switch to Cross. You can also drag a finger over squares to mark a whole line.
How do I win a puzzle?
Lay a single route that starts at A on the left side and leaves at B along the bottom. It must match every number along the top and right edges exactly. When it all fits, the map flashes.
Which size should I start on?
Pick the smallest 8x8 grid on Easy. The Type menu has twelve presets, going up to 15x15 at Easy, Tricky or Hard, and a custom option if you want something else.
What can I do when I am stuck?
Undo and redo have no limit, so back up to the last move you trusted. Look for rows or columns whose count is already met and cross out the rest. If you just want the answer, the Solve button shows it.
