The board rules
- Each row has the same number of suns and moons.
- Each column has the same number of suns and moons.
- You cannot place three identical symbols in a row, column or diagonal line of three.
- Equal and different clues between cells must be respected.
Use pairs to force the third cell
Two matching symbols next to each other force the cells immediately before and after them to be the opposite symbol. For example, if two suns are side by side, neither neighbour can be a sun. This is one of the fastest ways to turn a sparse board into a solvable one.
Count before you guess
On an even-sized row, half the cells must be suns and half moons. If a row already contains its allowed number of suns, all remaining blank cells are moons. The same applies to columns. Count frequently because a completed line can unlock clues elsewhere.
Read clues in both directions
An equal clue means the two connected cells match; a different clue means they do not. Once one side is known, the other is known too. A clue can matter even when neither cell is filled yet, because it links the possible values of two lines.
A calm solving order
First look for pairs and near-complete lines. Then use the equality and difference clues. Finally count each row and column again. Repeating that order keeps the puzzle logical and avoids random taps.