How to play Sightlines
Shade some squares so every number sees exactly that many white squares along its row and column, counting itself. Also known as Visibility shading, Lookout numbers.
The rules
- Squares with numbers stay white.
- A number counts the white squares visible from it — up, down, left and right — up to the first shaded square or the edge, including its own square.
- Shaded squares never share a side.
- All white squares are connected to each other through sides.
Playing Sightlines on Puzzle Solvers
- Choose a size and a difficulty, then press New Puzzle.
- Tap a square to shade it, again for a white dot, again to clear. Drag to do several. Right-click places a dot.
- Tap a number to light up the squares it can currently see.
- Hint explains the next deduction — squares a number must see, views that are already full, and keeping the white squares joined.
Using the Sightlines solver
- Choose the size and type the numbers (or press Sample).
- Press Solve and step through: what each number must see, where its view must stop, and keeping the white squares joined.
A worked example
In a 5×5, a 9 in the centre can see at most 4 + 4 + 1 = 9 squares — so its whole row and column are white.
A 2 in a corner sees itself and one more square, so one neighbour is white and the next square along is shaded — the other neighbour is shaded.
Strategies
- Must see. If the other three directions can show at most 3 squares and the number is 6, it must see at least 2 squares in the fourth direction.
- Seen enough. When a number already sees its total, the squares just past its views are shaded.
- Next to shaded. Every square beside a shaded square is white.
- Stay joined. Never shade a square that would cut the white squares into two groups.
- Big numbers. A number close to the maximum (rows + columns − 1) sees almost everything — its row and column are nearly all white.
Common mistakes
- Forgetting to count the number’s own square.
- Shading two squares that touch along a side.
- Cutting off a white area with a line of shaded squares.
Where it comes from
Visibility shading puzzles of this kind were first published by the Japanese puzzle company Nikoli and are popular with logic-puzzle fans.
Frequently asked questions
Do numbers see diagonally?
No — only along their row and column.
Is there always one answer?
Yes — every puzzle here is checked to have exactly one solution.
What do the dots mean?
A dot marks a square you know is white. It is optional but helps you keep track.
How do I solve one from a book?
Open the Sightlines Solver, type the numbers and press Solve.
Keep going
- Play Sightlinesa fresh puzzle every time
- Sightlines Solverstep by step, every move explained
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