Binary Puzzle
Two marks on a six-by-six grid. Never three alike in a line, and an even split in every row and column.
Fill every square with one of two marks.
Tap a square once for a filled dot, again for an open ring, once more to empty it. Shaded squares are fixed and will not change.
Tap a square once for a filled dot, again for an open ring, once more to empty it. Shaded squares are fixed and will not change.
Two of a kind side by side is fine. A third touching them — reading across or down — turns that run red until you break it up.
Six squares, three of each mark. Place a fourth of either and the whole line is flagged until you take one back.
On the hardest boards a bar joins two neighbouring squares. A solid bar means the two hold the same mark; a bar with a gap in it means they hold different marks. Break the bar's rule and both squares turn red.
Tap cycles · drag paints · keyboard: arrows move, space cycles
Got it — play