Each number is a measured line of sight, shade the grid black until every clue can see exactly the count of white cells it demands.
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How to play
Numbered cells stay white and fixed. You shade the remaining cells black so that the view from every number, counted along straight lines, matches its clue and the whole board stays consistent.
A number counts the white cells it can see in the four straight directions, itself included once, stopping at the first black cell.
Shade cells black so each number sees exactly its value in white cells.
No two black cells may sit edge to edge.
All white cells must stay connected as a single region.
Conflicts glow red live; solve when the shading matches the unique answer.
Controls
Desktop: left-click a non-number cell to cycle white, black, then unknown; right-click jumps straight to black (or back to white). Use Hint, Clear and Check from the toolbar.
Phone & tablet: tap a cell to cycle white, black and unknown; the unknown mark helps you pencil in uncertain cells.
Game modes
Daily: one shared puzzle a day at 5x5, 7x7 or 9x9.
Practice: endless freshly generated grids.
A timer and hint counter feed the leaderboard; Check briefly flags any wrong cells so far.
Tips & strategy
A small number boxed in by edges needs blacks placed close to cut its sightline down to size.
A large number must keep long open lines, so its rows and columns stay mostly white.
Lean on the no-touching rule: once a black is set, its four neighbours are forced white.
Origins
Numbered white cells whose clue counts the cells visible in straight lines, with the rest shaded, is Kurodoko — published by Nikoli under the name Kuromasu, literally "where are the black cells?".
The count includes the numbered cell itself and runs in all four directions until a shaded cell stops it, while shaded cells may not touch each other and the white cells must stay connected.
Counting along a line is what gives the puzzle its long reach. A clue does not describe its neighbourhood but a cross stretching across the board, so a single number can constrain cells nowhere near it — and the connectivity rule then ties those distant deductions back together.
About Sightline
Sightline is a free browser version of Kurodoko, the classic line-of-sight counting puzzle that turns simple counting into deep deduction, with every board guaranteed to have one solution. Daily and practice modes, free in the browser.
A free, original browser game on PlayPendium. No download, no install.
