The rules
Fill a 6×6 grid. Every cell holds a sun or a moon:
- Every row and every column has exactly three suns and three moons.
- No three identical symbols may sit in a row, horizontally or vertically. Two side by side is fine.
- An = sign between two cells: both hold the same symbol.
- An × sign between two cells: they hold opposite symbols.
Every puzzle has exactly one solution. You can reach it by logic alone, without guessing.
How to play here
- Click a cell to cycle between empty, sun and moon.
- Keyboard: arrows to move, 1 for sun, 2 for moon, Space or Enter to cycle, Delete to erase.
- Undo: Ctrl+Z. Redo: Ctrl+Y.
- Cells that break a rule are marked with diagonal stripes.
Difficulty levels
| Level | What it takes |
|---|---|
| Easy | Signs, pairs, gaps and counting |
| Medium | + Counting with × pairs |
| Hard | + Checking every option for one or two lines |
| Expert | + Checking full lines three times or more |
Techniques
Signs
Once one side of a sign is filled, the other side follows: the same symbol next to =, the opposite symbol next to ×.
Pair
Two identical symbols side by side, for example two suns. The cells on either end must be moons, or there would be three in a row.
Gap
Two identical symbols with an empty cell between them, for example sun, empty, sun. The middle cell must be a moon.
Counting
If a row already has three suns, every empty cell left in it is a moon. The same goes for columns.
Counting with ×
Two empty cells joined by × always hold one sun and one moon. Say a row still needs just one more sun, and it has an empty × pair. The missing sun is in the pair, so every other empty cell in the row is a moon.
Line check
When there is no simple step, pick a line with few empty cells. Go through every legal way to complete it. A cell that gets the same symbol in all of them is fixed.
Tips
- Always start with the signs and the pairs. They open most of the grid.
- After placing a symbol, check its row and its column.
- In a line with only two symbols missing, try both options in your head.