Masyu: the pearl loop puzzle

Masyu, the pearl puzzle

Masyu is a loop puzzle with only two kinds of clue: black pearls, where the loop must turn, and white pearls, where it must go straight. Work out how the loop passes each pearl and one single closed loop appears.

Play unlimited masyu puzzles free online, from small starter grids to large, tricky boards. If you like it, try slitherlink next: another single-loop puzzle, driven by numbers instead of pearls.

Where Masyu comes from

Masyu is a loop puzzle published by Nikoli. The name is often translated as “evil influence”. The grid holds white and black pearls, and you draw a single closed loop that passes through every pearl, following simple rules at each one.

How to play here

Drag through the grid to draw the loop, and drag over a segment again to remove it. The loop moves between the centers of cells, horizontally and vertically, never crosses or touches itself, and must end up as one closed ring through every pearl.

The pearl rules

• White pearl: the loop goes straight through it, and turns in at least one of the cells just before or after it.
• Black pearl: the loop turns on it, and goes straight for at least one cell on both sides of the turn.

A step-by-step way to solve

1. Start at the edges. A black pearl next to the border cannot turn toward it, so its direction is often forced.
2. Look at white pearls in a row. Three white pearls in a line cannot all be crossed in the same direction, which forces them to go across.
3. Extend black pearls. Once you know which way a black pearl turns, draw two cells straight out in each direction.
4. Mark cells the loop cannot use. Dead ends and cells that would create a small separate loop are out.
5. Keep one loop. Near the end, avoid closing a small loop that leaves pearls outside it.

Why play Masyu?

Masyu has only two symbols, yet it produces some of the most elegant solves in logic puzzles. If you like drawing loops, try Slitherlink next; if you prefer paths, try Zip.

How to play Masyu

1. Draw a single closed loop through the centers of the cells, moving up, down, left and right. The loop never crosses or touches itself.
2. The loop must pass through every pearl. It doesn't have to visit every empty cell.
3. At a black pearl the loop turns 90°, and it goes straight for at least one more cell on both sides of the turn.
4. At a white pearl the loop goes straight through, and it turns in at least one of the two cells next to the pearl.

Masyu tips

Start at the edges

A black pearl one cell from the edge can't send its straight arm toward the wall, so the loop must leave it the other way. Edge pearls usually give the first sure lines.

Look for white pearls in a row

Three white pearls in a line can't all be passed straight along that line, because the loop would have nowhere to turn. So the loop crosses each of them the other way.

Mark cells the loop can't use

Cross out edges that would close a small loop too early or break a pearl rule. On masyu, what the loop can't do is often clearer than what it does.

Frequently asked questions