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Rules -- Circumnavi-Gates

Circumnavi-Gates was invented by the Japanese puzzle company Nikoli (under the name Suraromu).

1. Draw a single loop, starting and ending at the numbered circle. The loop may only travel horizontally or vertically, and never diagonally (so all turns are of 90 degrees). The loop may only turn at the centers of the grid cells. The loop may not cross itself or branch off. In other words, the interior of the loop will be a single polygon.
2. The dotted lines are called gates. The loop must pass straight through every gate exactly once, by traversing exactly one cell in each gate. (The number in the circle represents the total number of gates, and is included as a convenience.)
3. A numbered black cell represents the order in which the loop passes through the gate which touches that black cell. (If a numbered black cell is next to more than one gate, then the number refers only to the gate which has that same number on both ends.) A gate numbered 1 must be the first gate visited in the loop, starting from the circle and going in one of the two possible directions, a gate numbered 2 must be the second gate visited, and so forth. The other gates may be passed through in any order.


hagriddler said...

Hello, I have just discovered your very nice puzzle site and I love it !

If I understand Circumnavi-Gates correctly I have one addition to the rules :

"The loop must pass straight through every gate exactly once" suggests that every gate MUST be used.
But only the mentioned number of gates should be used, so there can (and often will) remain unused gates.

Grant Fikes said...

hagriddler: Read rule 2 carefully: "The number in the circle represents the total number of gates, and is included as a convenience." The loop must pass through every gate. The number in the circle is included as a convenience only, to save the solver from having to count the gates.

Suppose there's a gate numbered 52, for example. Wouldn't be be convenient to know that there are exactly 53 gates in the puzzle, so you know that the 52nd gate is also the second from the last gate? Instead of forcing you to count all of the gates to determine there are 53, I'll just tell you that to save you some trouble.

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