how to play day & night
Day & night is a free daily logic puzzle about balance. Fill the grid with suns and moons so every row and every column holds the same number of each, and never put three of the same next to each other in a line. Some edges between squares carry a sign: = means the two squares hold the same thing, and × means they hold opposites. Every board has exactly one answer, and you can always reach it by reasoning, never by guessing.
- Tap an empty square once for a sun, twice for a moon, and a third time to clear it. The squares that start filled are locked.
- Every row and every column needs exactly half suns and half moons.
- Never three suns or three moons in a row, across or down.
- Two squares joined by = must match; two joined by × must be opposite.
- Anything that breaks a rule gets red stripes, and a broken sign turns red. Fill the grid with nothing broken to stop the clock. Stuck? A hint costs 10 seconds.
Keyboard: Arrow keys move around the grid, S or 1 places a sun, M or 2 places a moon, Enter or Space cycles a square, Backspace or 0 clears it, Z undoes, H asks for a hint, and Esc goes back to the menu.
tips
- Two suns side by side? The squares on either end must be moons. A gap between two suns? It must be a moon.
- Once a row has its half of suns, everything left in it is a moon.
- A × between two squares means that pair holds one of each, which counts toward the line's half and half.
- On normal and hard, look at a whole row: if only one arrangement fits what's there, every square it agrees on is settled.
faq
Is there always one solution?
Yes. Before you see a board, our solver finishes it step by step without guessing, which proves the answer is unique. A second, separate counter checks samples of our boards too.
What do the levels mean?
Easy is 6 by 6 and needs only the simple rules. Normal is 8 by 8 and needs you to reason about whole rows and columns. Hard is 10 by 10 and needs at least one what-if: if this were a sun, a rule would break, so it's a moon. The daily is the same for everyone and climbs through the week: monday is a gentle 6 by 6, the middle of the week is 8 by 8, and the weekend goes to 10 by 10, with sunday needing a what-if.
How is it scored?
By time. A hint clears any wrong squares or fills the next square you could work out, and adds 10 seconds to your time. The clock pauses while the tab is hidden.