Fence Loop is the classic loop puzzle played by shading. Instead of drawing line segments, you paint the cells that lie inside the fence; the fence itself appears around the painted area. A number in a cell tells you how many of that cell’s four sides are part of the fence. Every puzzle here is generated fresh and checked by a solver so that it has exactly one answer.
How to play
The rules.
- There is exactly one fence, a single closed loop that never crosses or touches itself.
- A number in a cell says how many of its four sides are on the fence: 0 means none, 4 means the cell is fenced on all sides.
- The area outside the grid is outside the fence, so a border cell that is inside has at least one fenced side.
Shading. Tap a cell to cycle through three states: inside (painted green, with the fence drawn around the painted area), outside (a small dot, your own note), and empty again. You can also select a cell and use the ■ Inside and · Outside buttons, or Erase. On a keyboard, I or X paints inside, the full stop marks outside, and Backspace clears; the arrow keys move between cells.
Outside marks are only notes. The puzzle counts as solved the moment every inside cell is painted, whether or not the rest is dotted.
Mistakes and help. A number is highlighted when the cells you have painted around it already fence too many of its sides, or leave too few sides that could still be fenced. Hint fixes a wrong cell if you have one, otherwise it paints one correct cell. Undo takes back your last change. The timer and the number of hints you used appear when you finish.
Difficulty. Choose under Difficulty at the top; New puzzle creates another grid at that size.
| Level | Grid | Numbers shown |
|---|---|---|
| Easy | 6 × 6 | about half the cells |
| Medium | 8 × 8 | about 40% |
| Hard | 10 × 10 | about 30% |
Strategy
Zeros and fours. A 0 has the same state as all four neighbours (and a 0 on the border is outside). A 4 is an inside cell surrounded by outside cells, a tiny island of its own.
Think in sides. A corner cell that is inside already has two fenced sides, so a corner 1 is outside, a corner 3 is inside with exactly one inside neighbour, and a corner 2 has both neighbours inside whether the corner itself is inside or out. A 3 on an edge that is inside has one more fenced side on the border, so only one of its three inner neighbours is inside.
Follow the fence. Every painted area must stay in one piece and every unpainted area must reach the edge of the grid. If painting a cell would leave an unpainted pocket that cannot reach the edge, that cell is outside; if leaving a cell unpainted would split the inside, it is inside.
Adjacent numbers. Two 3s side by side share a fenced side between them and are fenced on their far sides: one is inside, the other outside. Two 2s in a diagonal often force the fence to turn around them.
If you enjoy Fence Loop, try Flip Lights or Futoshiki next.
