Daily Skyscrapers Sudoku
The extra rule
A clue outside the grid says how many buildings are visible from there.
Read each digit as the height of a building. A clue outside the grid tells you how many you could see standing there and looking along the line, with taller buildings hiding every shorter one behind them.
A 1 is the strongest clue on the board: the nearest building must be a 9, because nothing else could hide the other eight. A 9 is just as good, because the line has to climb 1 to 9 in order.
Short clues work from the far end too. A 2 means the 9 sits somewhere behind exactly one taller-than-anything-before-it building, which rules the 9 out of the first place in the line.
Controls
Click a cell and type a digit, or use the pad. Space toggles pencil marks. Arrow keys move. Progress saves in this browser as you go, so you can come back to the same puzzle later today.
Solvable Without Guessing
Every puzzle here was generated and then handed to a solver that is only allowed techniques a person can use. If it could not finish the grid without a guess, the puzzle was thrown away rather than published. That also makes the answer unique, because every digit it placed was forced.
More to Play
There is also a kropki sudoku, a xv sudoku, a greater than sudoku, a nonogram with hand drawn pictures, and 2048. All of them are on the games page, and the solvers for real objects are on the puzzle tools page.