Binary

What is Binary?

Binary is a calm logic puzzle in two digits. The board is a square grid with a few 0s and 1s already in place. Fill every empty square with a 0 or a 1 so that three rules hold everywhere: never three equal digits side by side, as many 0s as 1s in every row and column, and no two rows or two columns alike.

Every board has exactly one solution, and it can always be reached by reasoning, never by guessing. Boards come in three sizes, 6 by 6, 8 by 8 and 10 by 10, and a new board, the same for everyone, arrives every day.

How to play

Tap an empty square to write a 0, tap it again for a 1, and once more to clear it.

• Given digits. The solid squares are part of the puzzle and cannot change; your own digits are outlined.
• Three rules. No three equal digits next to each other in a row or column; half 0s and half 1s in every row and column; no two rows alike and no two columns alike.
• Red digits. A digit turns red while it breaks a rule, so mistakes show at once.
• Score. Your score is the time to solve the board, plus 30 seconds for every hint. Every board size has its own leaderboard.

Strategy tips

1. Close the pairs. Two equal digits side by side must have the other digit at both ends.
2. Fill the gaps. An empty square between two equal digits takes the other digit.
3. Count the line. Once a row or column has all its 0s, every empty square left in it is a 1, and the other way round.
4. Read the whole line. When a line is nearly full, try each way to finish it; a square that comes out the same in every way is certain.
5. Look for twins. On the large board, a line one or two digits from matching a full line must differ exactly where it is still open.

FAQ

Is Binary free to play?

Yes. Like every game on Play, it runs free in your browser, with no download and no account needed.

Do I ever have to guess?

No. Every board is checked by a solver that only deduces, so a logical next step always exists.

What does a hint do?

It writes one right digit: it fixes a wrong digit first if there is one, otherwise it fills the easiest square to deduce. Each hint adds 30 seconds to your time.

What is the daily board?

Every day everyone plays the same medium 8 by 8 board, so times compare directly on the leaderboard.

How is my score counted?

Your score is the time from the first look at the board to the last right digit, plus 30 seconds for every hint. Lower is better.