What Is Masyu? Rules and Beginner Strategy for the Pearl Loop

What is Masyu?

What is Masyu at heart? It is a single loop puzzle built around pearls. You are given a grid dotted with white and black circles, and you must draw one continuous loop that passes through every pearl. The loop travels horizontally and vertically between cell centers, never crossing itself and never branching. What makes Masyu special is that the two pearl colors give opposite instructions about how the loop must behave as it passes through, which turns a plain loop into a puzzle full of forced turns and straights.

The white and black pearl rules

Masyu has just two clue rules, and learning what is Masyu really means learning these by heart.

• The loop must pass straight through every white pearl, but it must turn in at least one of the two cells directly next to that pearl.
• The loop must make a right angle turn at every black pearl, and it must go straight for at least one cell on both sides after leaving it.
• The single loop passes through all pearls, never crosses itself, and never branches.
• Cells with no pearl can be straight, turned, or skipped by the loop entirely.

Beginner strategy

The clearest way to grasp what is Masyu asks of you is to work outward from the black pearls first.

1. For each black pearl, check the borders, because a black pearl near an edge or corner has forced directions when it needs two straight cells leaving it.
2. For white pearls in a straight line, neighboring whites often force the loop to zig zag in a predictable way.
3. Draw the segments a pearl forces, then follow the loop where it is now committed.
4. Cross out directions that would break a pearl rule to narrow the next move.
5. Keep checking that you are not about to close a small loop too early.

Reading pearls near the edges

Edges and corners are where Masyu puzzles usually crack open. A black pearl in a corner has only one way to make its right angle and still travel two cells in each direction, so its whole neighborhood is fixed at once. A white pearl on the border cannot turn toward the wall, which limits where the loop can bend. Training your eye to spot these edge cases first will speed up nearly every Masyu you attempt.

Avoiding early loops

As with other loop puzzles, the biggest trap in Masyu is accidentally sealing a small loop that leaves pearls unvisited. The loop must be one single circuit through every pearl, so before you connect two ends, make sure you are not fencing off part of the grid. Marking impossible connections is just as valuable as drawing certain ones, because elimination is what exposes the next forced turn or straight.

From pearls to shapes

Masyu and Sudoku share a gentle promise. Every move is deducible, so there is never a need to guess. If the calm of tracing forced turns appeals to you, Shapedoku offers the same no guessing logic with a warmer face. It keeps the classic row, column, and box rules but replaces the digits one through nine with nine glowing shapes, friendly to the eye and to colorblind players. Try the free daily challenge at app.shapedoku.com or watch the logic unfold with the solver on shapedoku.com.