Binairo
Suns and moons. No three alike in a row, and every row and column balanced.
How to play Binairo
Every square holds a sun or a moon. Three rules decide where they go.
- No more than two of the same symbol in a row, across or down.
- Each row and each column has the same number of suns and moons. On an 8×8 board that is four of each.
- No two rows match exactly, and no two columns match exactly.
The squares that start filled are locked. Everything else is yours to fill in, change and undo.
Three moves worth knowing
- Pairs need a cap. If two suns sit side by side, the squares on both ends must be moons.
- Sandwiches. If a sun, an empty square and another sun line up, the middle one has to be a moon.
- Count the row. When a row already holds its full share of suns, every empty square left in it is a moon. Run the same check on columns.
When those run dry, check for twins. If another row already matches a finished row everywhere except two empty squares, those two squares cannot both take the copying values.
Questions
What are the rules of Binairo?
Fill every square with a sun or a moon. No more than two of the same symbol may sit next to each other in a row or column. Every row and every column holds the same number of suns and moons. No two rows are identical, and no two columns are identical.
Is Binairo the same as Takuzu or Binary Puzzle?
Yes. The rules are the same. Different publishers use 0 and 1, black and white, or suns and moons.
Does every puzzle have exactly one solution?
Yes. A solver checks that exactly one answer fits, and a second solver that reasons like a person has to be able to finish the board using pair caps, sandwiches, line counts and the no-copies rule. If it cannot, the board is thrown away.
Is my progress saved?
Your board, timer and streak stay in your own browser, and clearing site data removes them.