數迴

Loop the Loop: rules and solving techniques

Use the clues to draw one unbranched closed loop around the grid. This guide reflects the controls and win conditions in the current browser build. It is reviewed by the PocketJoy game-testing team and maintained by Long-Term New Media Limited.

The rules

A Loop the Loop board is a lattice of dots, with some of the cells between them carrying a number from 0 to 3. You draw line segments along the edges between dots so that all of them together form exactly one closed loop — a loop that never branches, never crosses itself and is never broken, with only one such loop on the whole board. The number in a cell states how many of that cell's four edges are part of the loop: a cell marked 3 has exactly three of its edges drawn, a cell marked 0 has none at all, and cells without a number are unconstrained. Clicking an edge cycles it between three states — segment, cross and blank — where the cross marks an edge you have determined will never carry a line. Three difficulty levels are available. Press check when you are done and the game confirms the loop or tells you that the segments do not yet form a single correct loop. Both your move count and your time are recorded.

Advanced solving

Starting from the 0s and 3s is the standard opening. A cell marked 0 has crosses on all four edges, which is free certain information and immediately constrains its neighbours. A 3 does the opposite, carrying three lines, and in combination with its neighbours it often fixes edges outright. Several classic patterns are worth committing to memory. Two 3s that touch diagonally force lines on their two opposite outer edges. Two 3s adjacent horizontally or vertically force a line on the edge they share, and also on each of their far outer edges. When a 3 and a 0 touch diagonally, the two edges of the 3 nearest the 0 carry no line while the two far edges do. A 1 in a corner of the board has a useful property: its two edges on the outer rim must be crossed, because the loop cannot travel outside the board. Beyond the numeric clues, the more powerful tool is loop connectivity. Since only one loop may exist, any drawing that would close a small circle early is wrong. Check periodically for dot degree: every dot must have either zero or exactly two lines meeting it. One line means the path is unfinished; three means something is definitely wrong. That degree rule frequently outperforms the number clues as a source of deductions.

Common blind spots

The most common mistake is watching only the number clues and forgetting the loop constraint itself. Plenty of positions satisfy every number while producing two separate small circles, which is illegal — there must be exactly one closed loop. Building the habit of checking dot degrees after each segment heads off those dead ends early. The second mistake is drawing lines without ever using crosses. A cross records that an edge definitely carries no line, and in Loop the Loop that negative information is as valuable as the positive kind, particularly when judging whether a dot is already closed; without crosses you will re-derive the same conclusion repeatedly. The third is guessing a segment on instinct and building on it. The solution is unique, so a wrong guess produces its contradiction somewhere distant and the backtracking is expensive; draw only what you can prove, and move to another region when you cannot. The fourth is neglecting the board edges. Cells on the rim have one fewer neighbour and are therefore more constrained, and the four corners are usually the easiest cells on the board.

Who it suits best

Loop the Loop suits players who enjoy pure deduction and take pleasure in pattern recognition. It belongs to the same family as sudoku and nonograms but feels quite different to solve: sudoku is about what goes in a cell, while Loop the Loop is about whether an edge is drawn, with an additional topological constraint that the result must be a single closed loop. That extra dimension makes the reasoning richer than a straightforward number-filling puzzle. It takes some patience to get started, because the classic patterns — adjacent 3s, a diagonal 3 and 0, a corner 1 — are not things intuition hands you and have to be learned. Once they are, you find yourself reading whole regions at a glance, and that shift from not knowing where to begin to having patterns leap out is deeply satisfying. There is no luck: each puzzle has a unique solution and every step is deducible. Easy puzzles run five to ten minutes and hard ones considerably longer, with no time pressure and the freedom to stop and think.

Feature highlights

Three difficulties are available with a fastest time stored for each in the records panel. The sidebar shows move count and elapsed time together, and the two measure different things: time reflects how quickly you think, while move count reflects how precisely you reason, since trial and error inflates it noticeably. The check button validates whether your segments already form a single correct closed loop, and when they do not it says specifically that the loop is not yet correct rather than merely reporting failure, telling you the problem lies in the loop structure rather than in a mismatched number. A hint button settles one step when a position has you stuck. The three-state edge cycling — segment, cross, blank — lets you record negative information on the board instead of holding it in your head. Completion shows your total time and offers a fresh puzzle.

Controls and record keeping

There is one interaction: tap an edge between two dots and it cycles through segment, cross and blank. That single action covers both drawing and marking, so there is no mode to switch and no distinction between mouse buttons, which makes desktop and phone play identical; on a phone the tappable area of each edge is enlarged so neighbouring edges are not caught by mistake. A mis-tap costs nothing — tap twice more to return to blank. Fastest times and move counts are stored in the browser's local storage on your own device, never uploaded to a server and requiring no account; clearing browser data removes them. The language button switches between Traditional Chinese and English instantly, including every prompt and check result. Once loaded, the game itself plays offline.

Rules Q&A

Reviewed by the PocketJoy game-testing team · Operated by Long-Term New Media Limited · hklongtermad@gmail.com