Expert Train Tracks Puzzles

The biggest grids, the fewest clues

Expert puzzles use a 12×12 grid, and our generator removes every given piece that is not needed for a unique solution. What is left is often just A, B and a few scattered pieces, so almost every deduction starts from the numbers.

These grids are guaranteed to have exactly one solution, checked by an exhaustive solver. Unlike the other levels, they are not capped at a particular technique, so some need long chains of reasoning or several nested “what if” steps.

Strategies for expert grids

Divide the grid. Parity across every horizontal and vertical cut gives you a skeleton of where the route must cross, and the row and column totals tell you how much track each band can hold.

Track the loose ends. At any moment the route is a set of fragments; count their loose ends and make sure each can still reach a partner without closing a loop or finishing the route early.

Take breaks. Coming back to a stuck expert grid with fresh eyes works better than forcing a guess, and your progress is saved in your browser.

Printable expert puzzles

Large grids are often more comfortable on paper. The printable expert page puts two puzzles on each sheet with the answers at the back.