Fence Loop

The dots are fence posts and the numbers are counts: a cell marked 3 has exactly three of its four sides fenced, a 0 has none at all. Join the dots until the fence is a single closed loop — no gaps, no spurs, no second loop wandering off on its own. Every board has exactly one answer, and the board tells you where you stand the whole way: each number shows a tick the moment it is satisfied, and the status line names the shape you have actually drawn.

It runs entirely on your device: 0 network requests, works offline. No ads, no account, nothing to buy, and no betting, money or prizes of any kind.

1. Focus the board — click it, or press Tab until it is focused.
2. Walk from dot to dot with the arrow keys. The edge you have just walked along is the selected one; it is outlined, not merely tinted.
3. Press Enter to cycle that edge: blank, then a drawn line, then crossed out, then blank again. Shift cycles the other way, which is the quick route from blank straight to crossed out.
4. Click an edge to do exactly the same thing, if you would rather use a pointer.
5. Watch the moves. Drawing a line costs one move, and so does taking one away. Crossing an edge out is free, so rule edges out first and only draw what is left — that is the cheap way through, and it is also how the puzzle is meant to be solved.
6. Close the loop before the moves run out. The counter above the board says whether the lines are nothing yet, some number of loose ends, two separate loops, or the one closed loop you want.

How do you solve a loop puzzle where each number counts its own edges?

Start with the certainties and let them spread. A 0 fences nothing, so cross out all four of its sides immediately — that is free, and it usually settles a neighbour. A 3 in a corner has both outer sides fenced, because only two of its sides can reach anywhere else. Two 3 cells side by side always share the wall between them plus their two far sides. After that, work from the dots rather than the cells: a dot is only ever touched by nought or two lines, so a dot with one line arriving must have exactly one more leaving, and a dot with two already is finished — every other edge at it can be crossed out. The last tool is the loop itself: any line that would close a small loop early, while numbers elsewhere are still unmet, is wrong, because the answer is one loop that uses every fenced edge on the board.

Is every board guaranteed to have exactly one answer?

Yes, and both halves of that are checked before you see it. The loop is drawn first and the numbers are read off it, so an answer exists by construction. Then numbers are rubbed out one at a time and each removal is kept only if a solver — which counts every possible loop on the lattice, stops at two, and never looks at which loop we started from — still finds precisely one. Nothing is dealt that could be finished two different ways, and nothing is dealt that cannot be finished at all.

Where does the move budget come from?

From the solver, not from a designer's guess. The floor is the loop's own length, because every edge of the answer has to be drawn exactly once. On top of that you get a small fixed allowance plus one extra move for every number the solver proved it could rub out — each of those is a deduction you now have to make instead of read, so each one buys you a correction. The budget is therefore always achievable and always tight enough that guessing loses.

Why does crossing an edge out cost nothing?

Because it commits nothing. A cross is you recording that an edge cannot be fenced, which is the move that actually solves this kind of puzzle, and charging for it would push players towards drawing lines speculatively — the exact habit the game exists to break. Lines are the claim, so lines are what the budget meters.

What do the ticks and crosses on the numbers mean?

A tick means that number is currently satisfied: it has exactly as many fenced sides as it asks for. A cross means you have overshot it and one of those lines has to go. A number with neither shows how many of its sides are drawn so far, as a fraction. None of this depends on telling colours apart — every state carries a glyph, and the numbers stay full-contrast on their tinted cells.

Is there any money, betting or in-app purchase in this?

None, and there never will be. No currency, nothing to buy, no lives to refill, no wager of any kind.

Does it work offline?

Yes. Once the page has loaded once, the whole game is on your device — rules, boards, solver and all. There is no server involved in play at any point, and no board is ever fetched.

Can I play it with a keyboard or a screen reader?

Both. Arrows walk the lattice, Enter and Shift mark the selected edge, and the board publishes a full parallel description: every edge is announced by the cell and side it belongs to along with whether it is blank, a line or crossed out, and every number is announced with how many of its sides are currently drawn.

Four cells by four, so twenty-five dots and forty edges. Boards are drawn from the 9,028 loops on that lattice that are at least twelve edges long and that their own numbers pin down uniquely, out of the 9,349 loops that exist there in total. At least six numbers are always left printed: a sparser board is still solvable, but it leans on the single-loop argument in ways that are no fun to meet first. Losing reveals the answer, dashed on the board.

Light Grid is the other planning puzzle here — it asks you to reason about parity rather than about counts, and its move budget is derived the same way. Mini Sudoku is the pure elimination one, where every step is "this cannot go here" and nothing has to be drawn.

Bookmark this page (Ctrl+D, or ⌘D on Mac) or install the app — it works offline the next time you need it.