About Binary Grid
Binary Grid is a logic puzzle also known as Takuzu or Binairo. It uses only two symbols, which makes it look simpler than sudoku. It is not. With three rules working together, every square can be deduced, but you have to keep all three in mind.
How it works
The grid is six by six, with fourteen squares given at the start. Each puzzle is generated with exactly one solution, so guessing is never necessary. If the grid breaks a rule, your entries turn red and the status line says so. It does not tell you where, which keeps the puzzle honest.
Techniques, in order of usefulness
Pairs. Whenever two of the same digit sit side by side, the squares at both ends of the pair must hold the other digit. Otherwise there would be three in a row. Look for pairs first, in rows and in columns.
Gaps. If two of the same digit have one empty square between them, as in 1 _ 1, the middle must be the other digit, for the same reason.
Counting. Each line has three of each. As soon as a row has its three 1s, every remaining square in it is a 0. This is the rule beginners forget, and it finishes more lines than any other.
Counting ahead. If a row has two 1s and needs one more, check each empty square: would putting the last 1 there force three 0s together somewhere else? If so, it cannot go there.
Duplicates. The rule about identical lines matters only near the end. When a row is complete and another row matches it everywhere except two empty squares, those two must be filled the opposite way.
Apply them in a loop: pairs, gaps, counts, then round again. It is the hardest of the number HTML5 games here and well worth learning.