Skyscraper practice sheets
Two parallel lines, a shared column, and two roofs that cannot both be empty. Every puzzle here needs at least one skyscraper.
A missing corner, not a broken X-Wing
A skyscraper is what an X-Wing looks like when one of its four corners is gone. Take one digit. Find two rows in which the digit has exactly two candidate cells — the same starting scan as an X-Wing. If two of those four cells share a column, the pattern still works, even though the fourth corner is somewhere else entirely.
Why it works: in each of the two rows, one of the two cells must be the digit. The shared column can only hold it once, so at least one of the other two cells — the roofs — must be the digit. Those roofs sit in different columns. Any cell that sees both of them therefore cannot hold the digit, and those cells are where the elimination happens.
Why drill it separately
Skyscrapers are rarer than X-Wings and much rarer than pairs, so in mixed puzzle sets you meet one every ten grids at best, usually at the moment you are already frustrated. That is the worst possible time to learn a scan. This sheet puts the pattern in every puzzle, at a difficulty where nothing else is going on to distract you from it.
Each puzzle is generated, replayed cheapest-technique-first, and kept only if a skyscraper is used on that path. The set is regenerated in your browser every visit.
What the grader guarantees
Every puzzle needs at least one skyscraper. Nothing on the sheet asks for more than one tier above it, so the worst extra step you can meet is a swordfish or a chain — expected on a sheet this hard, and the place where the guide's later chapters earn their keep.
Finding them faster
- Scan by digit, not by cell. Pick a digit that is already placed several times; count its homes per row. Two-home rows are the raw material for both X-Wing and skyscraper.
- Look for the shared column early. Two two-home rows that happen to line up in one column is the whole trigger. Once you have found the shared base, the roofs are just the two cells that are left.
- Eliminate along the roofs' columns. Not the base column. Getting this backwards is the usual failure, and it feels plausible — which is why it survives unnoticed.
With Candidate marks printed, the counting is reading rather than remembering, and one puzzle per page leaves room to mark the four cells with a pencil.
Related practice
The full guide to skyscraper has a worked example, the proof, and the difference between a skyscraper and a two-string kite — they are easy to confuse because both start from the same scan.
If the pattern feels slippery, go back one step: X-Wing practice gives you the rectangle first. For the three-line version of the same idea, swordfish.