Rules
The board is a grid. Some cells hold a white pearl or a black pearl. Draw lines through the centres of cells that share a side.
- One closed loop. Lines join the centres of cells that share a side, across or down, never diagonally. The loop does not cross, branch, or touch itself.
- Every pearl. Every white pearl and every black pearl is on the loop. Empty cells may stay off it. A cell on the loop has two lines. A cell off it has none.
- Black pearls. On a black pearl the loop turns, and both arms go straight through the next cell. The loop cannot turn in the cell immediately after the pearl.
- White pearls. On a white pearl the loop goes straight through. It turns in at least one of the two cells beside the pearl. It may turn in both.
- Blank edges. A cross means “not a line”. A segment you leave blank, off the loop, does not need one. Check treats the loop as solved while those edges are still blank.
In the picture the centre cell is off the loop. The white pearl runs along the top, and the loop turns in both cells beside it, so “it may turn in both” is on the page. One turn would have been enough. Each black pearl is a corner, and each arm is two segments in a row: through the next cell, and on one cell further. The loop is teal because it is finished. The four edges around the centre are still blank, and that is allowed.
- White pearl
- Black pearl
- Line
- Cross
Every puzzle here has one solution, and you can finish it by logic. Easy grids follow from the pearls. Medium grids also follow the line through empty cells. Hard grids stop the loop closing too early, and some of them add an even count across a cut.
Pearls
Two black pearls that share a side stay apart. Three white pearls in a line turn across it. A white pearl on the border runs along the border.
Side by side Easy
Two black pearls that share a side cannot be joined by the loop. Cross the edge between them. Each pearl sends its arms the other way.
Hint looks for this pair before any other pearl. The cross stays muted. The amber band is the segment this step writes. The same cross applies when the pair sits side by side in a row.
6×6 easy and 6×6 medium grids here do not contain the pair. A 6×6 hard grid can, and an 8×8 grid can. Use it when you see it, then go back to the border and the corners.
Three in a line Easy
Three white pearls in a straight line cannot be one straight run. The loop goes through each of them at right angles to that line.
In a row, that means a vertical through each pearl, and crosses on the row between them. The picture shows the first segment. The next eight marks are the same idea: they finish the three verticals and the crosses between the pearls before any other technique. In a column, the rule turns: a horizontal through each pearl.
Do this when you see the three. 6×6 easy and 6×6 medium grids here do not contain them. Some 6×6 hard grids do, and 8×8 grids do.
On the border Easy
A white pearl on the edge of the grid cannot go straight off the board, so it runs along the border. Draw both segments through the pearl, and cross the side that points inward.
The first segment runs to the right. The next two finish the pearl: the line to its left, then the cross inward. Start here on a 6×6.
This mark is the easy pearl rule. On the finished loop in section 1, the same three marks come first, and the black pearls finish that grid. Here the empty cells still have to be followed, which is section 4. A white pearl in the very corner has no border run that stays on the board. That case is a mistake in section 7, and the cell stays quiet until a bend is drawn.
A blocked way
If one way through a white pearl is closed, take the other. One side of a white pearl still has to turn. A black pearl sends both arms straight through the next cell.
The other way is blocked Easy
A white pearl runs across or down. If a cross, or the border, has already closed one of those, the loop takes the other. Draw both segments through the pearl and cross the two sides of the dead axis.
The white pearl on the edge already runs along the top, and the cross under it is the inward side. The pearl below cannot go vertical, so it runs across. One line already touching the pearl is enough to know the direction, once the other axis is dead. The next two marks finish it: the line to the left, then the cross below.
One side has to turn Easy
The loop goes straight through a white pearl, and it has to turn in at least one of the two cells beside it. If one of those cells is already straight on, the other side is the turn: cross the segment just past that cell. If the cell beside the pearl is another white, it cannot be the turn, so the line keeps going and the turn is on the other side.
Both through-lines have to be on the board before this step. A blank grid does not start here.
The neighbour is a white pearl
The three marks already on the board are the border rule for the left-hand white pearl. The next cell is also white, so the loop cannot turn there. The line continues one cell further. The turn on the left is the corner at the end of the row, which section 4 draws later. There is no cell past that corner to cross.
One side already runs straight
The line already runs through the white pearl and keeps going through the white beside it, all the way to the corner. That side does not turn. The right side does, in the next cell, which crosses the segment after it. The cross stays muted.
The corner and both arms Easy
A black pearl is a corner. Each arm then goes straight through the next cell, two segments in a row, and the loop does not turn in that next cell. If one direction would leave the board, or would have to turn, that direction is not an arm.
Up and left leave the board, so the corner is right and down. The picture shows the first segment. The next five marks finish this pearl before the other black is touched: the line on through the right-hand cell, the cross that keeps that cell straight, then the same shape downward.
With the first segment drawn, the arm continues to the edge of the grid. The following mark is the cross under that next cell, the “do not turn here”. A black in the corner of the grid has only one possible corner. Draw both arms as soon as you know them.
A 6×6 easy grid is often full of black pearls, and a black one cell in from a wall is the usual place to look. A 6×6 easy grid finishes with the border, a white whose other way is blocked, a turn once one side is settled, and black corners with both arms. Neighbouring blacks and three whites in a line are the same family, and Hint looks for them first, and 6×6 easy grids here do not contain them. Medium is the next section. Hard is the early loop, and on some grids the even cut.
Follow the line Medium
Use this when the pearls have stopped. A cell with one line and only one open side continues through that side. A cell with two lines is full, so its other sides stay empty. A cell with no line and only one open side is a dead end, so that side stays empty. Empty cells count.
One line, one open side
The border pearl is already drawn. The corner cell has its one line, to the right, and only one side left, so that side is a line. The next hint is the same sentence on the other corner.
Two lines already meet
The bottom cell of the open box has a line on the left and a line above, so the side to the right stays empty. The cross stays muted. This move is the medium rule. The grid is not finished yet: section 5 is what closes it.
No line, one open side
Left, right, and above are already crosses, and the cell has no line, so the side below stays empty. Easy grids never need this section. Every medium grid does. When these three have stopped, a hard grid still has section 5.
What if the loop closed Hard
Use this only when the pearls and the line have stopped. Look at an empty segment whose two ends are already connected by lines. If drawing it would close a loop while a pearl is still outside, that segment is a cross.
The six cells close a loop, and the white pearl stays outside. Check turns that pearl red. The line you tried is not listed as a bad edge. Erase it anyway.
The two ends are already connected, and a pearl is still outside. That segment is a cross. Draw the cross. Do not try a second segment inside the first try.
The whites on the loop still fit, so they stay ordinary. Only the pearl outside turns red. Draw the cross. Do not leave the line in place. Do not try a second segment inside the first try. Easy and medium never need this. Every hard grid here does. Some of them finish on this step alone, and Hint never mentions an even cut.
An even cut Hard
Use this only when sections 2–5 have stopped. The loop is closed, so any straight cut between two rows, or between two columns, is crossed an even number of times: 0, 2, 4, and so on. If one gap on that cut is still open, the count decides it.
| Gap on the cut | Before the move |
|---|---|
| r2c1–r3c1 | Empty. This is the line. |
| r2c2–r3c2 | Cross |
| r2c3–r3c3 | Cross |
| r2c4–r3c4 | Line |
One line is an odd count, so the empty gap becomes a line and the cut is crossed twice. An even number of lines already drawn would leave the gap empty. Count only the segments that cross the cut, not every line on the board. The mark just before this one is the dead-end cross from section 4. The mark after it comes from a black pearl, not from a second cut. Some hard grids never need this. On those, Hint stays with the early loop.
Medium adds following the line. Hard adds the early loop on every hard grid here. The even cut is the extra step, and some hard grids never use it.
Common mistakes
Check paints a broken cell or a bad loop while error highlight is on. A cell with one line is unfinished, not an error. An empty edge off a finished loop is not an error. Crosses stay muted.
A white pearl bends
Two lines on adjacent sides make a corner. A white pearl has to run straight through. Check marks the pearl.
Three lines meet
A cell on the loop has two lines. A third line is a branch, even when the cell has no pearl.
Both neighbours stay straight
The white pearl itself runs straight, which is right, but both cells beside it are straight too. At least one of them has to turn.
Straight through a black pearl
A black pearl is a corner. A straight run through it is already broken, and Check marks the pearl.
The next cell already turns
The corner at the black pearl is fine. The cell to its right then turns down, so that arm is no longer straight.
A white pearl in the corner
Both directions run off the board, so the pearl cannot go straight and still turn. With the bend drawn, Check marks it. There is no loop to draw.
The same pearl, nothing drawn
The corner white is impossible, and Check stays quiet while no line is drawn. The cell stays quiet until a bend is on the board.
A loop that misses a pearl
The boundary is one loop and the black pearls fit. The white pearl is off it, so Check turns that pearl red. The loop stays violet: the grid is not solved.
A small loop, and another line
The four edges close a loop while a stray line is still on the board. The loop’s edges turn red. The stray line is what makes them illegal, and the stray itself is not in the list.
A cross on a line the corner needs
The edge does not turn red. Hint still asks for the line on that same edge. A wrong cross is set aside before Hint looks, so it is not the start of the next step.
A line either loop could use
This black pearl has two loops. The violet line is in one of them and not the other, so nothing turns red and Hint stays quiet. The line between the corner and the next cell is in both, which is a different question.
What to play next
Each card is a size the play page lists. The idea on the card is the one that level adds.
- EasyPearlsStart with white pearls on the border and with black pearls in the corners. Go straight through a white whose other way is blocked, and turn on the side that still can. When two blacks share a side, or three whites sit in a line, cross between the blacks and turn across the whites.Play Easy →
- MediumFollow the lineWhen the pearls stop, follow the line. Two lines in a cell close its other sides. One line and one open side continue. A cell with no line and one open side stays empty.Play Medium →
- HardEarly loop, then a cutIf a line would close the loop while a pearl is still outside, cross that segment. If one gap remains on a cut between two rows or two columns, the even count decides it.Play Hard →
6×6 comes in easy, medium and hard. 8×8 comes in medium and hard. The daily is a 6×6 easy grid: today’s daily or open that size.
Print from the Masyu packs. A 6×6 sheet holds four puzzles. An 8×8 sheet holds two. Large print is one grid.
- GuideHashiJoin islands with bridges and keep one group.
- GuideSlitherlinkOne loop around the clues. Start from the 0s and 3s.
- GuideLight UpLight every cell. Start beside the 4s and 0s.
- GuideBinairoPairs, gaps and balanced lines of 0s and 1s.
- GuideSudokuRows, columns and boxes, from singles to triples.
- GuideKakuroOne-way sums, then short runs and longer lists.
- GuideNonogramsOverlap long clues and cross the gaps.
- GuideStar BattlePlace stars so none of them touch.