Game guide
How to play Sun and Moon (Takuzu)
Sun and Moon is a logic puzzle, also known as Takuzu or Binairo. You fill the grid with suns and moons until it meets three rules, with no guessing.
Updated on October 3, 2026
The rules in 3 lines
- 01
Half of each
Every row and every column has the same number of suns and moons.
- 02
Never three in a row
In a row or a column, at most two suns (or two moons) side by side.
- 03
No two rows alike
No two rows can be identical, and no two columns either.
How to play
On your phone
- Tap an empty cell: it becomes a sun.
- Tap again: it becomes a moon. One more tap: it is empty again.
- Cells with a beige background came with the grid and cannot change.
- Three of the same in a row turn red right away.
On a keyboard
- ← ↑ → ↓ move between cells.
- Enter or Space cycles empty → sun → moon.
- Esc closes the “⋯” menu.
Step-by-step example
Two techniques solve a good part of the grid. The first: two of the same side by side are flanked by the other symbol.
Before
After
The second: an empty cell between two of the same takes the other symbol.
Before
After
And this is what the game marks in red:
Wrong
Beginner strategies
- Start with pairs and sandwiches. The two techniques in the example give you safe moves right away.
- Count. In a row of 6 cells, once there are 3 suns, everything else is a moon.
- Switch between rows and columns. Every symbol you place can open up a move in the other direction.
- Save rule 3 for the end. If two rows are almost the same, the unfinished one has to end up different.
Common mistakes
- Guessing when stuck. The grid has a single solution, and logic always gets you further. Look for a count you have not done yet.
- Forgetting the columns. All three rules apply to columns too.
- Carrying on with a red cell. Red means three of the same in a row. Undo it before you continue.
- Filling the grid and stopping. If the grid is full and the game says it is not right yet, a row or column repeats another one or has the wrong count.
Levels and scoring
The size is the level: 6×6 on Easy, 8×8 on Medium and 10×10 on Hard. Every grid is generated on the spot and has exactly one solution. Your record is your best time on each size.
Frequently asked questions
Yes, with the same three rules. Here the symbols are a sun and a moon instead of 0 and 1.
The cells with a beige background came with the grid. They are the clues that guarantee a single solution.
No. Every grid has exactly one solution, and the three rules are enough to find it.
Yes. Your game is saved on this device and shows up as “Continue” in the games list.
IQNorth games are a pastime with a challenge. Practice makes you better at this game; it does not raise your IQ or your memory, and nothing here is a consultation with a psychologist. The games are in the member area.
Guides for the other games
Sudoku · Word search · Colors · Sequence · 2048 · Challenges · Blocks · Pairs · One Line · Shape Fit · Sum Maze · Pipes
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