Sight Lines

What is Sight Lines?

Sight Lines is a quiet logic puzzle about looking out across a harbour at night. Some squares of the grid hold numbers, and every number is a lamp that looks up, down, left and right along its row and column. It counts every open square it can see, itself included, until a shaded square or the edge of the grid stops its view, and it must see exactly as many squares as it shows. Your job is to shade the squares that stop the light. Around the world the puzzle is also known as Kurodoko, or Range.

Every board has exactly one answer, and it can always be reached by reasoning, never by guessing. Boards come in three sizes, 7 by 7, 9 by 9 and 11 by 11, and a new board, the same for everyone, arrives every day.

How to play

Tap a square to shade it, tap again to put a dot on it as a reminder that it stays open, and once more to clear it. Drag across the grid to paint a whole run of squares the same way in one move.

• The view. Each number sees along its row and column in all four directions, counting itself, up to the first shaded square or the edge. That count must match the number exactly.
• Apart. Two shaded squares never touch side by side, and a number is never shaded.
• Together. All the open squares stay joined, side to side, into one piece.
• The beam. Tap a number to light its beam across the board and see exactly how far it reaches. A number glows once it sees its count, and anything that breaks a rule turns red, with the line under the board saying which rule.
• Score. Your score is the time to solve the board, plus 30 seconds for every hint. Undo is free, and every board size has its own leaderboard.

Strategy tips

1. Start with the big numbers. A number close to the most it could ever see must see far in every direction, so the squares nearest to it are open.
2. Count what is sure. Once a number already sees its full count through open squares, the next square in each direction must be shaded.
3. A 1 shades its neighbours. A 1 sees only itself, so every square beside it is shaded.
4. Shadows keep their distance. Every square beside a shaded square is open.
5. Never cut the harbour in two. A square whose shading would split the open squares into separate pieces must stay open.
6. Weigh the ways. When a number could share its count out in a few ways, look for a square that every way agrees on, or a way whose end square cannot be shaded.

FAQ

Is Sight Lines free to play?

Yes. Like every game on Play, it runs free in your browser, with no download and no account needed.

Do I have to dot the open squares?

No. Dots are only notes for yourself; the board is solved the moment the squares you have shaded follow every rule.

What does a hint do?

It fixes a wrong mark first if there is one; otherwise it makes the next step that follows by logic and says which rule it used. Each hint adds 30 seconds to your time.

What are tonight's lights?

Every day everyone plays the same medium 9 by 9 board, so times compare directly on the leaderboard.

How is my score counted?

Your score is the time from the first look at the board to the last shaded square, plus 30 seconds for every hint. Lower is better.