How to Do a Masyu Puzzle

So, you probably have never heard of a masyu puzzle - but it is never too late to learn!

A masyu is similar to a slitherlink (which few people have heard of...) but instead of having numbers to use as clues it has pearl-like clues.

"Masyu (ましゅ Mashu?, IPA [maʃɯ]; translates as "evil influence")[1]) is a type of logic puzzle designed and published by Nikoli. The purpose of its creation was to present a puzzle that uses no numbers or letters and yet retains depth and aesthetics." ~Wikipedia~

"Masyu is played on a rectangular grid of squares, some of which contain circles; each circle is either "white" (empty) or "black" (filled). The goal is to draw a single continuous non-intersecting loop that properly passes through all circled cells. The loop must "enter" each cell it passes through from the center of one of its four sides and "exit" from a different side; all turns are therefore 90 degrees." ~Wikipedia~

So, with a little insight from Wiki, lets get onto the gameplay!

Before we move on, I would like to shout out to http://krazydad.com/masyu/ for providing hundreds of puzzles for free!

The rules are simple:

1. A black circle must have a line turning a corner on it, this line must continue one dot after each side of the circle.
2. A white circle must have a straight line through it, this line has another condition, it must turn a corner one dot after the circle on either one of the ends or both of the ends.
3. The line made must go from dot - to - dot or dot - to - circle or circle - to - dot, there are no diagonals.
4. The line must go in a full loop, both ends connecting.
5. The line cannot overlap itself or branch off.
6. Every change of direction other than straight has to be at a 90* angle.

This step outlines what to do and what not to do.

I will explain the grid in a coordinate form, the columns (vertical) are lettered and the rows (horizontal) are numbered.

You will notice the picture is divided horizontally leaving two puzzles on top and two on the bottom of the sheet.

The two top puzzles are incorrect.

The two bottom puzzles are correct.

Neither of the four puzzles are complete though, this allows me to explain a bit easier.

The top left puzzle has four problems, left to right they are as follows:

1. B-3 White circle has a corner in it.
2. C-3 White circle has a corner in it.
3. E-1 Black circle does not continue two dots after the circle.
4. E-3 White dot does not have a corner after one or both the ends.

The top right puzzle has three problems, they are as follows:

1. A-6 The line cannot continue the loop.
2. D-2 The white circle does not have a corner after one or both the ends.
3. F-4 The black circle does not continue two dots after the circle.

So, the bottom two puzzles are correct, see if you can see where the top puzzles are wrong.

From here on in I will explain my method of solving these little neat puzzles, there will be one picture per step and I will explain what is happening.

The picture here shows you the puzzle I started with, at the time of photographing a puzzle this size took me about 8 minutes - now it is about 2 minutes!

So, we start with the edges first,

The edges are in most cases the easiest to solve.

If a black circle is on an edge one of it's branches go into the middle of the puzzle.

If a white circle is on the edge of the puzzle the line goes parallel with the edge of the puzzle.

Note on picture, *&*;

There is an "X" here because the line cannot continue vertical, if it did the white circle would not have its corner.

Now I go through the puzzle and fill in the obvious parts.

I look for the rest of the lines that can be put on the edges and I also check for more than two white circles in a row.

Here is when I start joining the obvious lines.

There are some lines that almost create circles, I put little "X"'s here to remind me they cannot join.

Now is about the stage where I have joined enough to get a relevant shape of the loop I am making.

I am currently working on two long loops in the photo and am just looking for anomalies.

There is a note over one of the few anomalies I found in this photo, it shows you the kind of thin you are looking for.

When I get to this stage I start identifying anomalies and start fixing them up.

I have a note over the anomaly I spotted in the last step, I joined it where it is supposed to go to.

At about here the puzzle is at its hardest.

You will notice a second note box pointing out another anomaly, here, if I connect the wrong lines, there will be a mini-loop.

So, we check through the puzzle for anything we missed earlier, there are a lot more lines to work off now!

The note here is on a line that is surrounded by lines, it can only go one way.

This is where the puzzle gets a little easier.

About this time is when I start joining any major loops I have.

I was working on two loops and now have found where they join.

This is where the puzzle gets super easy again.

I finish off the major loops and now can wok on finishing the whole puzzle.

When I am finished my pile of puzzles I run across the room to the printer and print off another 50!

So, there you have it - A step by step guide on solving masyu!

Thanks for reading, please share this awesome puzzle and please also take a moment to vote for me in the "how to play" challenge!