Knight Trail: protect the next exit, not just the next square
Compare legal moves by the unvisited exits they preserve, and use a short teaching trail to understand when backtracking is more useful than starting over.
Worked examples use the Standard board unless a different size is stated. Hard and Expert may change the board dimensions or amount of information to track.
Describe the L before selecting its landing
A knight changes one coordinate by two and the other by one. On a five-wide teaching board, a knight at row 1, column 1 can reach row 2, column 3 or row 3, column 2. A nearby square in the same row is not legal, even when it looks convenient.
The knight jumps over intervening squares. Only the landing needs to be unvisited. Keep that distinction separate from the trail itself: earlier landings remain unavailable, but crossing an imaginary line between them does not create a collision rule.
Count the exits that remain unvisited
A corner of that five-wide board has only two geometric exits, while the centre has eight before any squares are visited. As a trail develops, those totals shrink. Count unvisited legal landings from a candidate square rather than judging it only by its distance from an edge.
A square with few remaining exits deserves attention. Leaving it until late may make it unreachable without revisiting somewhere else. However, always choosing the smallest count is a heuristic, not a proof that the resulting trail will cover the entire board.
Follow a route without mistaking it for an answer
Consider this teaching sequence: 1,1 to 2,3 to 4,4 to 5,2 to 3,1. Each move changes the row and column by one and two in some order, and none repeats a landing. The sequence explains legal movement; it is not a suggested opening for the generated start you currently see.
After reaching 3,1, inspect the unvisited options from there. Then inspect what each option would leave available afterward. Looking one decision beyond the next landing can expose a route that enters a narrow region without leaving any way out.
Backtrack to a decision you can change
When no legal unvisited landing remains, Undo removes the latest move and makes that square available again. Continue backward until you reach a position with another choice. Simply selecting an earlier visited square does not backtrack; it is still an illegal landing until those later moves are undone.
Use the visible step numbers to remember which branch you tested. Restart discards the entire trail but preserves its starting square. New puzzle may select another starting endpoint through a finite rotation, reflection or reversal of the verified route family.
Finish a tour without adding a closing rule
Standard asks for all 25 squares, Hard 36 and Expert 64. Completion is an open tour: the last square does not need to lead back to the starting square. Adding that extra condition would create a different challenge from the one implemented here.
Every offered starting square has at least one complete route because it comes from a checked full tour. Your own partial trail can still reach a dead end. The useful habit is to preserve options and explain your backtracking, rather than assuming that a solvable start makes every legal continuation safe.
An original guide for this site's implementation. Found an unclear step? Let us know.