About Sun & Moon
Sun & Moon is a binary puzzle: every square holds one of two symbols. Each row and column must hold as many suns as moons, and no three of the same symbol may sit together in a line. Signs between some squares tell you whether a pair matches or differs.
How to play Sun & Moon
- Fill every square with a sun or a moon. Tap a square to cycle sun, moon, empty.
- Every row and every column holds as many suns as moons.
- No more than two of the same symbol may sit next to each other in a row or column.
- An = between two squares means they are the same; × means they are different. Fastest time wins.
Tips & strategy
- Two equal symbols side by side mean the squares at both ends must be the other symbol.
- A single gap between two equal symbols must hold the opposite symbol.
- Count: once a row has all of its suns, every empty square left in it is a moon.
- Follow chains of = and × signs. One known square can settle a whole chain.
- Work on the rows and columns with the most symbols already placed; they have the fewest ways to finish.
Sun & Moon: questions and answers
What do = and × mean?
= means the two squares hold the same symbol. × means they hold different symbols.
Is there always one solution?
Yes. Every board is checked to have exactly one solution.
How is Sun & Moon ranked?
By time. The fastest correct solve wins.
How big is the grid?
Six by six on easy and medium days, and eight by eight on hard days, when there are also fewer starting symbols.
Can I tell the symbols apart without colour?
Yes. Suns and moons have different shapes, and the signs between squares are printed as = and ×.