Skyscraper Sudoku (PuzzleMadness)

About Skyscraper Sudoku (PuzzleMadness)

The ordinary sudoku rules apply: 1 to 9 once in each row, column and 3x3 box. Imagine each digit as a skyscraper with that many floors. A clue outside the grid tells you how many skyscrapers you would see looking along that line from that side: a building is visible only if it is taller than every building in front of it. In the site's example, looking down the first column you see the 6, then the taller 8, then nothing more until the 9, which gives a clue of 3.

The clues are strongest at the extremes. A clue of 1 means the 9 stands right at that edge. A clue of 9 would mean the line runs 1 to 9 in order. The 9 is always visible and hides everything behind it, so only the cells before the 9 count towards the clue.

The grid works like every sudoku on PuzzleMadness: number buttons above and below it, an eraser, and a pencil mode for candidate digits. On a keyboard, the number keys enter digits, the arrow keys move between cells, Ctrl, Shift or Alt with a number adds a pencil mark, and Delete or Backspace clears a cell.

PuzzleMadness is a free puzzle website run by Dewi, a software developer who started out making games for the PlayStation 2, Nintendo Wii and DS and now builds the site as a hobby. It carries dozens of puzzle types, from classic sudoku to newer logic grids, and each one gets its own dated puzzle every day at each difficulty. Skyscraper Sudoku comes in Easy, Medium, Hard and Tough versions plus a Mixed page, and the same day's Skyscraper Sudoku puzzle is shared by everyone who opens it.

The site checks your grid as you go and tells you when it is finished; it does not publish solutions. Each completed puzzle earns a score, and scores feed a monthly and an all-time Skyscraper Sudoku leaderboard, where only your best attempt at a puzzle counts. Older days stay in the archive, so a missed puzzle can still be played later and still counts toward the current month. Playing needs no account; a free registration gives you a username on the leaderboards and a cloud save. The pages carry adverts.

How to play Skyscraper Sudoku (PuzzleMadness)

1. Open today's Skyscraper Sudoku page on PuzzleMadness and choose a difficulty from the menu above the grid.
2. Click a cell and enter a digit with the number buttons above and below the grid or with the keyboard; the eraser button clears a cell.
3. Fill every row, column and 3x3 box with the digits 1 to 9, each once.
4. Treat each digit as a building of that height, and make the number of buildings visible from each clue match it; a building is hidden by any taller one in front of it.
5. Turn on pencil mode (the pencil button, or Ctrl, Shift or Alt with a number key) to jot candidate digits in a cell.
6. The site tells you when the grid is complete and adds your score; registered players appear on the leaderboards.

Tips

• A clue of 1 puts the 9 in the first cell from that edge.
• Everything behind the 9 is hidden, so only the cells in front of it can add to the count.
• High clues need a slowly rising line, so the first cell from that edge is usually small.
• Missed a day? Earlier puzzles are in the archive, and finishing one still counts toward this month's leaderboard.

Questions