How to play Yin and Yang
Fill every square black or white so that each colour forms one connected group, with no solid or checkerboard 2×2. Also known as Black and white groups.
The rules
- Every square gets a black or a white stone.
- All the black stones form one group, joined across or down.
- All the white stones form one group, joined across or down.
- No 2×2 block is all one colour, and no 2×2 block is a checkerboard.
Playing Yin and Yang on Puzzle Solvers
- Choose a grid size and difficulty, then press New Puzzle.
- Tap a square to cycle it: black, white, empty. Or pick the black or white tool and drag across squares.
- All the black stones must form one group (joined across or down), and so must all the white stones.
- No 2×2 block may be all one colour, and no 2×2 block may be a checkerboard. Hint explains the next stone.
A worked example
Three squares of a 2×2 block are black. The fourth cannot be black too, or the block would be solid — so it is white.
A white stone is boxed in by blacks on three sides; its only way to reach the other whites is through its fourth side, so that square must be white too.
Strategies
- Three of a kind. If three squares of a 2×2 block are the same colour, the fourth must be the other colour.
- Break the checkerboard. If a 2×2 block has two blacks on one diagonal and one white, the last square must be white.
- Don’t cut a group off. If a stone would separate some of its colour from the rest, it must be the other colour.
- Edges matter. Around the edge of the grid, each colour can only appear in one unbroken stretch — two separate stretches of the same colour would need to meet inside, crossing the other colour.
Common mistakes
- Forgetting the checkerboard rule.
- Leaving a single stone of one colour surrounded by the other.
Where it comes from
Two-colour connectivity puzzles like this appear in Japanese and Western puzzle collections under several names. This version always has a unique answer.
Frequently asked questions
Do diagonals count as joined?
No — stones join only across or down.
Why is a checkerboard not allowed?
In a 2×2 checkerboard, each colour touches only at a corner, so one of the two colours would be split.
Is there always one answer?
Yes — every puzzle is checked so that logic alone reaches the unique answer.
Keep going
- Play Yin and Yanga fresh puzzle every time
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All guides: How to play every puzzle and game.