Most frequent errors: black-pearl arms that turn after one cell, white-pearl turns placed two cells away, small loops closed too early, and pearls left off the loop. Turning on error highlighting catches all four instantly.
Rule mistakes
1 A black-pearl arm that’s too short
Each arm of a black pearl must pass straight through the next cell. Turning immediately after the pearl is illegal.
Fix: after drawing any black pearl arm, immediately mark ✕ on both sides of the arm’s first cell (arm locks).
2 Going straight through a black pearl
Usually happens when a long line is dragged across the board in one stroke.
Fix: draw black-pearl corners as two separate short strokes.
3 A white-pearl turn in the wrong place
The turn must be in a cell immediately before or after the white pearl. A turn two cells away doesn’t count.
Fix: once a white pearl’s line runs straight into a neighbour, check that the other neighbour turns (far-turn technique).
4 Turning on a white pearl
Fix: treat every white pearl as a short straight pipe. Decide horizontal or vertical first.
Loop mistakes
5 Closing a small loop too early
Joining two loose ends of the same segment creates a closed loop. Unless that loop already contains every pearl and every line, the puzzle can’t be finished.
Fix: whenever two ends of one segment are next to each other, mark ✕ between them (premature loops).
6 Leaving a pearl off the loop
Every pearl must be on the loop. A neat loop that skips one pearl is still wrong.
Fix: before closing the final gap, scan the board once for any pearl without a line.
7 Branches and dead ends
Every visited cell has exactly two lines. A third line creates a branch; a single line is a dead end.
Method mistakes
8 Not using ✕ marks
Recording where the loop can’t go is half of Masyu. Many “impossible” positions become obvious once the ✕ marks are there. Use right-click, Shift-drag, or ✕ mode on touch screens.
9 Guessing
Every puzzle on this site can be solved without guessing. A guess that happens to be right teaches nothing; a guess that’s wrong can hide for a long time. If you must test an idea, do it as a deliberate what-if chain and undo it if it doesn’t produce a contradiction.
10 Losing track of loose ends
On larger boards, solvers forget which ends belong to the same segment and accidentally close a loop. Trace each segment with your eye from end to end before connecting it to anything.
Our boards flag mistakes 1–7 in red as you play, and pearls glow green once they’re satisfied. You can turn both off in Settings when you want a pure challenge.