How to solve hard Binairo puzzles
10×10 and 12×12 boards aren't harder rules — they're longer chains. Here's how to keep your place.
Work the emptiest lines last
Sweep every row and column for bookends and gap fills first; they cost nothing. Only then look at counts.
Pip: A real 8×8 from the generator. Before counting anything, sweep: a bookend in row 4, a gap fill in row 7, a gap fill in column 2, two bookends down column 5 and a gap fill in column 7. Six cells, no counting.
Read-only example · 1 of 2
Count pressure on long lines
On a 12×12 each line needs six of each. When five owls are placed and four empties remain, ask which empties could still be an owl without making three in a row — often only one can.
Use notes for two-way cells
Long-press (or press N) to mark a cell you're reasoning about. Try one animal, follow the forced moves in your head, and see whether any cell ends up the same either way — that's chain reasoning, and it's the last tool you'll need.
Pip: The first cell can't be an owl — bookends forbid it. So it's a fox, and then count the foxes: two placed, one to go. Finish the row.
Interactive example · 2 of 2 · tap the empty cells
Try it
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