Binary is a logic puzzle played with just two digits. Fill every empty square with a 0 or a 1 until the grid follows three simple rules. Every puzzle has exactly one answer, and you never need to guess.
The rules
No more than two of the same digit next to each other in any row or column: 0 0 is fine, 0 0 0 is not.
Every row and every column has the same number of 0s and 1s.
No two rows are identical, and no two columns are identical.
How to play
Tap an empty square once for a 0 (blue), again for a 1 (orange), and a third time to empty it. The darker squares with a small dot are the clues, and they cannot be changed.
If something breaks a rule, it is outlined in red: three alike in a row, a line that already has too many of one digit, or a finished line that copies another. Undo takes back your last change, and Hint fixes a wrong square or fills in one you can work out next. On a keyboard, use the arrow keys to move and 0 or 1 to place a digit.
Three patterns that solve most puzzles
Pairs: next to two alike, the square must be the other digit. 1 1 means a 0 on each side.
Gaps: between two alike, the square must be the other digit. 0 _ 0 means a 1 in the middle.
Counting: once a line has all its 0s (half its length), every remaining square in it is a 1, and the same for 1s.
Thinking in whole lines
On Hard puzzles the patterns above run out, and you have to look at a whole row or column. Suppose a line still needs two 1s and three 0s. Try each way of placing them, and throw out any that would make three alike. Squares that come out the same in every remaining option can be filled in.
Use the no-repeats rule near the end. When a line is one digit pair away from matching a finished line, the order of that pair is forced the other way.
Difficulty levels
Easy: a 6×6 grid with plenty of clues. A good way to learn the patterns.
Normal: an 8×8 grid with as few clues as possible. The pair, gap and counting patterns are all you need.
Hard: a 10×10 grid with as few clues as possible, where you will need whole-line reasoning.
Every puzzle is newly made and has exactly one solution. Your best time is kept for each difficulty.