Skyscraper Sudoku: rules, strategy and how to start
Each digit is a building height, and the clue outside a row counts how many buildings you can see from that side. Taller buildings hide everything behind them.
Why the rule changes everything
A clue of 1 means the tallest building stands first — the 9 is pinned to that cell.
A clue of 9 means the row is in perfect ascending order from that side. Those two extremes solve more of the board than any other pair of clues.
The middle clues are weaker but combine well: two sides of the same row usually fix the position of the 9.
How to start a board
- Write down every 1-clue and place its 9 immediately.
- For a 2-clue, the 9 must sit in the second visible position relative to the nearer tall building.
- Check both directions of the same row: the pair of clues usually constrains the two ends first.
Common mistakes
- Adding the buildings instead of counting how many are visible.
- Forgetting that a building is hidden only by one that is strictly taller.
- Assuming the clue tells you the order of all nine digits.
Frequently asked questions
Where are the clues?
On the left of each row and above each column in this board.
What is the maximum clue?
9 — the row is sorted ascending from that side.
Every board on this site is generated with a uniqueness check, so the puzzle in front of you has exactly one solution and every digit can be proved rather than guessed.
Play Skyscraper Sudoku ↗