Loop Trace

A closer look at Loop Trace

A number belongs to a cell

Loop Trace uses the familiar numbered-cell single-loop mechanic. Each clue belongs to the square space between four dots and counts the line segments bordering that cell. A shared edge contributes to both adjoining cells. A zero has no bordering lines; a three has exactly three. Dots do not carry clues and do not all need to be visited. Our code, prepared clue sets and explanations are made for this site. We do not claim to have invented the common mechanic.

The answer must be one loop

Lines join adjacent dots horizontally or vertically. At a used dot exactly two segments must meet. A loose end has one segment; a branch has three or four. Unused dots may have no segments. All drawn lines must also belong to the same closed group. Two separate loops fail even if all nearby clue totals match. Numbers may sit outside the loop: the rule counts bordering sides, not enclosed cells.

Mark edges deliberately

Select an edge to cycle unmarked, line, cross, then unmarked. A cross is an optional note that an edge should stay empty. It contributes no line. You can finish with unused edges still unmarked. Every change adds one edit, including changing a line to a cross. Wrong lines remain editable: the controls are not a solver that accepts only correct choices.

Read the labels with a keyboard

Tab reaches the edge buttons; Enter or Space changes a focused edge. Right and Left move forward or backward through the labelled edge list without drawing. H identifiers describe horizontal dot rows and positions; V identifiers describe vertical row intervals and dot columns. Every button includes its orientation, coordinates and current mark in its label. Expand the edge and clue ledger to read the same information and cell counts without relying on colour.

Undo and retry mean different things

Undo last edit restores the previous set of marks and reduces Edits by one. Retry this board clears all marks and the history but keeps the current clues. Both controls are available after a win. A completed answer locks the edge buttons and moves keyboard focus to Undo. Check loop reports matching clues, line groups, open ends and branching dots. A partial count does not prove that your next edge is right.

A small paper example

Imagine four dots at the corners of a single square with a clue of three. Three of its four sides may be drawn, but that alone leaves an open path. A larger board must continue at the two loose ends through other edges to form one loop while keeping that cell at exactly three sides. Closing the fourth side would violate the clue. This paper example explains why a cell total and the whole-loop condition must be checked together; it is not a separate playable board.

A finite checked collection

New puzzle moves to another clue set in a finite seven-puzzle collection and resets the attempt; the collection eventually repeats. Each prepared three-by-three clue set has one valid closed-loop answer under these rules. Load beginner board restores the exact first lesson example. This is not an unlimited random generator, a claimed difficulty scale or a minimum-edit challenge. The independent beginner guide supplies a complete eight-line route and cell-by-cell check.

What the tab remembers

The marks, clue set and undo history stay in memory in this tab. Refreshing or closing loses your attempt. A fixed practice address reloads its example with no marks; an ordinary visit restarts the collection. There is no account, timer, payment, leaderboard or advertisement action required to play. No edge choice is submitted to our server, and the puzzle makes no promise about health or general ability.