Rules
Yin-Yang is a colouring puzzle. The board is a square grid. There are no numbers outside it. A filled circle is black. An outlined circle is white. Some cells start with a stone, and that stone stays. Every cell is black or white. All of the black cells join along their sides, and all of the white cells join along their sides. Touching on a corner does not join a group. No 2×2 block is a single colour. An empty cell is not white. You place a stone in every cell. The puzzle is finished when that colouring is the one solution and both groups still hold. Play is 6×6 through 10×10, each at easy, medium, and hard. The daily puzzle is a 6×6 easy grid. People also look this up as a yin yang puzzle.
Binairo also fills every cell black or white. There, each line is balanced and three in a row is forbidden. Here each colour is one group and no 2×2 is a single colour.
- Every cell is black or white. Every cell is black or white. A filled circle is black. An outlined circle is white. A stone that starts on the grid stays that colour. An empty cell is not white. Leaving a cell blank does not count as white.
- Each colour is one group. All of the black cells join along their sides, and all of the white cells join along their sides. Touching on a corner does not join a group.
- No single-colour block. No 2×2 block is a single colour.
A finished grid fills every cell. The frame is the solved frame. Black stones are the solved teal. White stones are pale teal with a teal stroke. The given stones keep a centred disc: yellow on black, violet on white. No yellow ring. No amber. A printed puzzle page draws only the given stones. A printed answer draws every stone. The print is black and white. It does not show the hint.
- Black
- White
- Given
- Finished
- Clash
The given mark in these pictures is a centred disc. The icon above puts a small dot in the corner. The finished picture uses the solved teal.
Choose Black or White under the board. Tap a cell, or drag across cells, to place that colour. Tap a cell that already has the colour to clear it. A cell with the other colour takes the new one. A drag follows the first cell: it places the colour, or it clears when that cell already has it. A given stone does not change. With a mouse, right-click places the other colour, or clears it when that colour is already there. Arrow keys move and stop at the edge. The first arrow, when nothing is selected, selects the top-left cell. Space or Enter places the selected colour, or clears it when the cell already has that colour. B or 1 places black. W or 2 places white. M switches Black and White. Backspace, Delete, or 0 clears the cell. There is no cycle through the colours. The pad reads "Tap to place. Right-click or M: other colour." Once the grid is solved it reads "Every cell is filled. Black is one group, and white is one group."
Press Hint for one step the rules already force, with a sentence saying why. Hint lights the cells it used, and it places one stone. One press writes one cell. Press Check when you want the board checked. A legal unfinished board gets "No mistakes so far. Keep going!" A broken board gets "A 2×2 is one colour or a checker, or a colour is split or sealed in. Look for the marked cells." Hint on a broken board gets "This board has a mistake, so there is no hint yet." If Hint finds nothing on a legal board, it says "No forced cell from here. A black or white stone may be in the wrong place, so try Check or Undo." Undo and Redo step through the moves. Reset clears the stones you placed. The given stones come back. When every cell matches the one colouring, the board turns teal. The dialog title is "Solved!" The dialog body is "Every cell is filled, each colour is one group, and no 2×2 is a single colour." The Mistakes counter counts how many times Check found a broken board. It is not a score.
A cell turns coral when a finished 2×2 is one colour or a checker, or when a colour is split into two groups or sealed away from the rest of its colour. Those marks appear only once the break is already forced. With error highlighting off, none of that coral is drawn.
The 2×2
Look at one 2×2. Three cells of one colour force the last cell to the other colour. Two diagonals cannot both be the opposite colour, so the empty cell matches the pair that is already one colour. A blank grid can open on either sentence. On the grid in this section, the 2×2 speaks first.
Three the same Easy
Three cells of a 2×2 are the same colour, so the last cell is the other colour. On this grid row 3 column 2, row 3 column 3, and row 4 column 3 are black, and they are givens. Row 4 column 2 is empty. It is white. The four cells are the square the sentence is about.
The toast is "Three cells of this 2×2 are the same colour, so the last cell is the other colour." This is the first press on this grid. Easy, medium, and hard all give this hint.
Yellow rings on row 3 column 2, row 3 column 3, row 4 column 2, and row 4 column 3. No amber. The new white has the open face and no given disc. The three black givens keep yellow centres. The grid is still unfinished. Hint says "Three cells of this 2×2 are the same colour, so the last cell is the other colour."
The two diagonals Easy
Two diagonals cannot both be the opposite colour, so this cell matches the pair. On this grid the black stones at row 2 column 4 and row 3 column 3 are one diagonal. Row 3 column 4 is already white, so the other diagonal cannot be white as well. Row 2 column 3 matches the black pair.
The square already spoke. Row 4 column 2 is the white from the first press, and row 3 column 4 is a white from the press after that. The article still teaches the 2×2 first. The figure shows the board as it is when this press fires. The sentence stays the same when the pair is white and the empty cell must be white. This picture writes black.
The toast is "These two diagonals cannot both be the opposite colour, so this cell matches the pair." Easy, medium, and hard all give this hint. The last press of this grid uses the same sentence and finishes the grid, so the toast is skipped. That press is not drawn.
Yellow rings on row 2 column 3, row 2 column 4, row 3 column 3, and row 3 column 4. No amber. The new black has no given disc. Row 2 column 4 and row 3 column 3 are given black stones, with yellow centres. Row 3 column 4 is the earlier white, with no given disc. The grid is still unfinished. Hint says "These two diagonals cannot both be the opposite colour, so this cell matches the pair."
The border
Once both colours already touch the outer edge, the cells between two stones of one colour are that colour when the other way around already holds the other colour. One press writes one of those cells. The cells that are still empty stay lit. Some grids open here. The article still teaches the 2×2 first.
Between two stones Easy
Both colours already meet the border, so the cells between two stones of one colour are that colour. On this grid a white stone sits at row 1 column 6 and another at row 6 column 6. A black stone sits at row 6 column 4, also on the border. The short way between the two white stones is the right edge: row 2 column 6, row 3 column 6, row 4 column 6, and row 5 column 6, all empty. The long way around passes the black stone, so that short run has to be white. The press writes row 2 column 6 only. The other three stay empty, and they stay lit. The sentence stays plural.
This grid opens here. The article still teaches the 2×2 and the diagonals first. Easy, medium, and hard all give this hint.
The same sentence writes one cell when the gap is a single empty cell. Later on this grid, row 1 column 3 and row 1 column 5 are black, and row 1 column 4 is the cell between them. The press writes row 1 column 4 black. After that write all three are stones, so the rings have no amber. The grid stays unfinished. Before that press, row 1 is three black stones, an empty cell, and two white stones. That press is not drawn.
The toast is "Both colours already meet the border, so the cells between these two stones are the same colour."
Yellow rings on all six cells. Row 2 column 6 is a new white stone, open face, no amber, no given disc. Row 1 column 6 and row 6 column 6 are given whites, with violet centres and no amber. Row 3 column 6, row 4 column 6, and row 5 column 6 stay empty: amber wash, yellow border, yellow ring, and no stone. The grid is still unfinished. Hint says "Both colours already meet the border, so the cells between these two stones are the same colour."
One way out
A group that is not the whole colour, with only one empty neighbour, has to grow into that neighbour when the same colour still sits outside it. Easy grids do not say this. The medium grid in this section opens on the border.
Only one empty way out Medium
A group with only one empty neighbour has to use it when the same colour still sits outside that group. On this grid row 5 column 5 is a white stone. Left of it, row 5 column 4, is empty. Right, up, and down are black. Other white stones sit outside this one cell, so the empty cell is white. Filling it black would seal this stone off.
Row 5 column 5 is a stone placed earlier. It is not a given. Row 3 column 5 is another white placed earlier. The givens include row 1 column 6 and row 2 column 3, which are the other whites outside the group.
This grid opens on the border, not on this press. The article still teaches the 2×2 and the border first. Easy grids do not say this. An easy grid does not offer this step. A hard grid gives the same hint.
The toast is "This group has only one empty way out, and the same colour still sits outside it." Later presses on this grid use the same sentence and finish the grid, so the toast is skipped. Those presses are not drawn.
Yellow rings on row 5 column 5 and row 5 column 4. No amber. Both are white stones. Row 5 column 4 is new and has no given disc. Row 5 column 5 is the earlier white, with no given disc. The grid is still unfinished. Hint says "This group has only one empty way out, and the same colour still sits outside it."
One cell, both colours
A cell that can no longer reach one colour takes the other. If that still does not write, try the other colour in one cell and keep the colour that can be finished. Easy and medium grids do not say either sentence. One hard grid opens on the cell that cannot touch. One hard grid opens on the try. The article still teaches the 2×2 and the border first.
It can no longer touch Hard
A cell that can no longer touch the rest of one colour takes the other colour. On this grid row 5 column 1 sits on the left edge. The cell above, the cell to the right, and the cell below are already white. It has no empty neighbour and no black neighbour, so it cannot reach the black stones. It is white. The press lights row 5 column 1 and every black stone already on the board. It does not light the white stones that wall it in.
Those three black stones are givens: row 3 column 4, row 4 column 3, and row 5 column 4. The white walls are givens too: row 4 column 1, row 5 column 2, and row 6 column 1. They get no ring.
This is the opening press on this hard grid. The article still teaches the 2×2 and the border first. Easy grids and medium grids do not say this. This picture writes white. A black stone can be forced the same way. The sentence here is the white one.
The toast is "This cell can no longer touch the other black cells, so it is white."
Yellow rings on row 5 column 1 and on the three black stones. No amber. The new white has no given disc. The three blacks are givens, with yellow centres. The white walls stay ordinary given whites, with no ring. The grid is still unfinished. Hint says "This cell can no longer touch the other black cells, so it is white."
The other colour fails Hard
Try the other colour in one cell. Keep the colour that can be finished. The sentence does not name the colour. On this grid the cell is row 2 column 4. It already touches three stones: white on the left, white on the right, and white below. Black cannot be finished there. Both colours are already on the border, and black splits one colour along that border. White can be finished. The press writes white at row 2 column 4 only.
Check would not paint that chain. The board is not full, and no group is sealed in. The sentence still covers a 2×2, and a later press shows that half. A later press on this grid writes black at row 1 column 5. Black can be finished. White fills the board and the white stones are split. After that black write, the grid is still unfinished. The sentence is the same. That press is not drawn. On another hard grid, white in one cell would finish a checker. The press writes black instead, and the grid stays unfinished. That press is not drawn.
This grid opens here. The article still teaches the 2×2 and the border first. Easy grids and medium grids do not say this.
The toast is "The other colour here cuts a group off or makes a 2×2 block."
A yellow ring on row 2 column 4 only. Open face, no amber, no given disc. Row 2 column 3, row 2 column 5, and row 3 column 4 stay ordinary given whites, with no ring. The grid is still unfinished. Hint says "The other colour here cuts a group off or makes a 2×2 block."
Common mistakes
Check paints a broken rule. Hint will not explain a board that is already broken. The toast is "This board has a mistake, so there is no hint yet." A wrong stone can also sit there with no coral at all. Then Check says "No mistakes so far. Keep going!" and Hint still offers the next real step. The wrong stone stays unless that step writes the cell. A direct call on a broken board can still return a step, because a mark that disagrees with the solution is set aside for that computation. The button does not make that call. The figures do not draw it.
Five pictures, all on the first grid. No amber and no yellow ring on the four broken ones. The quiet one shows the opening 2×2, because the board is legal. Coral is the cells the rule names. A finished 2×2 of one colour paints those four cells. A finished checker paints those four cells. A colour sealed into a corner paints that group, not the walls. A colour split on a full board paints every cell of that colour. The stone on a coral tile stays the ordinary stone. A given cannot be overwritten. The wrong colours sit on cells that start empty.
Row 4 column 2 is black. The solution says white. The 2×2 of row 3 column 2, row 3 column 3, row 4 column 2, and row 4 column 3 is all black. Those four tiles are coral. Three are given black stones, with yellow centres. Row 4 column 2 is a player black stone, with no given disc. The stones stay black. Nothing is amber, and there is no yellow ring. Hint says "This board has a mistake, so there is no hint yet."
This picture is not the blank board. It includes the two earlier whites, at row 4 column 2 and row 3 column 4. Row 3 column 4 is the correct white. Row 2 column 3 is painted white instead of the forced black. Those four tiles are coral. Row 2 column 4 and row 3 column 3 are given black stones, with yellow centres. The two whites have no given discs. The stones stay. Nothing is amber, and there is no yellow ring. Hint says "This board has a mistake, so there is no hint yet."
Row 6 column 1 is black, walled by white at row 5 column 1 and row 6 column 2. The edge closes the other two sides. Another black stone sits at row 6 column 6, so this black is not the whole colour. Only row 6 column 1 is coral. The walls are not coral. Row 6 column 6 is not coral, because it still has empty neighbours. The stone stays black, with no given disc. Nothing is amber, and there is no yellow ring. Hint says "This board has a mistake, so there is no hint yet."
The board is full. Row 1 column 5 is black instead of white. White is in more than one group. Every white cell is coral. The wrong black is not. The black stones stay ordinary. White stones on coral tiles stay outlined circles. The given whites among them keep the violet centre: row 1 column 1, row 3 column 1, and row 3 column 5. Nothing is amber, and there is no yellow ring. Hint says "This board has a mistake, so there is no hint yet."
With error highlighting off, the all-black 2×2, the checker, the sealed corner, and the split whites paint nothing coral. A full board that passes the checks you can see and still misses the colouring is not drawn here, and it can still occur.
Row 6 column 6 is black. The solution says white. It does not finish a 2×2, and it does not seal a group. No coral. Check says "No mistakes so far. Keep going!" Hint still places white at row 4 column 2, with yellow rings on the four cells of that 2×2 and no amber. The wrong black is not among them, and it stays. It has no ring, no coral, and no given disc.
A wrong black at row 1 column 6, which is white in the solution and is not the cell the step writes, is the same opening hint. A black at row 1 column 2 beside the given white at row 1 column 1 is legal. Two colours may share a side. Corners do not join a group. The opening hint is the same. An extra stone that matches the solution is not a broken board. The opening write simply omits that cell. Those stones are not drawn.
What to play next
Easy grids follow from one small patch of the board. Three cells of a 2×2 the same colour, two diagonals that cannot both be the opposite colour, and the cells between two stones once both colours meet the border. Start on a 6×6 easy grid. The daily puzzle is that size. Medium grids add the group with only one empty way out, after the earlier sentences. A medium grid still opens on a small patch. Hard grids add the cell that can no longer touch one colour, and the try. One 6×6 hard grid opens on the cell that cannot touch. One opens on the try. The others open on a small patch.
- Easy6×6The 2×2, the two diagonals, and the border. Some grids open on the 2×2. Some open on the border. This is the daily size.Play 6×6 →Today's daily →
- Medium6×6The one empty way out, after the earlier sentences. The grid still opens on a small patch.Play 6×6 →
- Hard6×6The cell that can no longer touch, and the try. One grid opens on the cell. One grid opens on the try.Play 6×6 →
A printed puzzle page draws the given stones. A printed answer draws every stone. Four 6×6 or 7×7 grids share a sheet. Two 8×8 or 10×10 grids share a sheet. A 12×12 grid has the sheet to itself. 12×12 is print only, at easy, medium, and hard. The printable page is Yin-Yang packs.
There is no guide-sized seed to open. The boards above are teaching boards.