The Doppit Almanac · No. 35

Fencit

Draw one closed loop past the numbers

What it is

Fencit is Slitherlink. You draw along the lines of the grid, not inside the cells, and what you are drawing is a single closed loop. Scattered through the grid are numbers from 0 to 3. Each one counts the sides of its own cell that the loop runs along, and a cell with no number is under no obligation at all.

Every corner of the grid carries two lines or none, never one and never three, so a line you draw in one place decides what can happen two corners away. Crossing sides out is half the work. A 0 rules out four sides at a stroke, and each side you rule out narrows the corners around it.

How it plays

• Draw a single closed loop along the grid lines. It never crosses itself and never branches.
• A numbered cell has the loop along exactly that many of its four sides.
• A cell with no number can have any of its sides on the loop, or none.
• Every corner carries two lines or none, and all the lines make one loop.
• Draw puts the loop on a side, Cross marks a side the loop skips. Tap a side, or drag along a run of them.
• Crosses are only your notes; the win ignores them. Stuck? Hint names the next forced side.

The difficulties

Easy is three by four, a dozen cells and about half a minute of counting sides. Medium is five by five and runs to roughly a minute. Hard is seven by seven, where the corner rule carries whole stretches of the loop on its own. Expert is ten by ten and carved thin, so most boards need at least one stretch where you follow a side through to a contradiction before you know which way it goes, and that one takes about five minutes. A fresh board is dealt every day in easy, medium and hard, for nothing, and expert is always there to practise on.

Nearby in the almanac: Pipeit, Trackit and Islandit