Sun & Moon (Takuzu / Binairo)

How to play

Sun & Moon is a binary logic puzzle, also known as takuzu or binairo. Fill every empty cell with a sun or a moon. Each row and each column must hold the same number of suns and moons, and no row or column may have three identical symbols next to each other. Some cells are joined by clues: = means the two cells hold the same symbol, × means they are different. The symbols already on the board are locked. Tap a cell to place a sun, tap again for a moon, and a third time to empty it. Broken rules light up in red right away. Every board has exactly one solution and can be solved by logic alone, without guessing. Play as many 6×6, 8×8 or 10×10 boards as you like: each size has its own leaderboard, and after every solve the next board of the same size is just one tap away.

Tips

• Look for pairs first: two suns side by side mean the cells on both ends must be moons, and the other way round.
• A gap between two equal symbols (sun, empty, sun) must be filled with the opposite one.
• Count: once a row or column has its full half of suns, every other empty cell in it is a moon.
• Follow the clues in chains: a known symbol next to an = or × tells you its neighbour, which often unlocks the next clue.
• Every board is ranked by time, so stay calm and let the red highlights catch your mistakes.