Every row and column holds the tower heights 1 to 5, once each. Each number printed outside the grid counts the towers you can see looking in from there: a taller tower hides every shorter one behind it.
Towers is a free daily skyscrapers puzzle from Mind Loft. Fill the grid with tower heights so that every row and every column holds each height exactly once, like a sudoku with no boxes. The clues sit outside the grid: each printed number counts the towers visible looking down that row or column from that side, because a taller tower hides every shorter one behind it.
There is no arithmetic, only lines of sight. A 1 pins the tallest tower right at its edge; a clue equal to the grid size forces the whole line to ascend toward you. Every board has a single solution you can always reach by logic, with no guessing, and a clean solve scores a perfect 10 with the daily leaderboard decided on the clock.
A new board drops every day at midnight Eastern: 5×5 on weekdays with fewer clues as the week goes on, and a 7×7 Sunday Edition. No app, no signup — play free in your browser. It runs with the sudoku family: try Towers, the skyscrapers puzzle, Sando, the sandwich sudoku with border clues of its own, and Polka, the kropki.