Hard printable sudoku
Twenty-nine clues. Rated hard when an X-Wing is the most the board needs — but only nine boards in six hundred actually top out there.
The honest version of "hard"
This setting is rated by the grader as X-Wing is the most expensive technique the solve needs. That is the definition. It is not the same as these puzzles need an X-Wing, and the gap between those two sentences is the most useful thing on this page.
Of the 600 boards this setting produced:
| Technique that topped out the solve | Boards out of 600 |
|---|---|
| Skyscraper | 354 |
| XY-Wing | 204 |
| Unique rectangle | 33 |
| X-Wing | 9 |
Nine. Against 354 skyscrapers. If you know what an X-Wing looks like and you have never heard of a skyscraper, this sheet will feel broken — puzzle after puzzle that resists every scan you know.
It is not broken. X-Wing is genuinely scarce. In a separate sample of 5,000 puzzles dug to 26 clues with no difficulty target, an X-Wing turned up in 3.5% of boards and a skyscraper in 10.1% — nearly three times as often, despite sitting after X-Wing in almost every teaching order. The full census has the numbers and the method.
What that means at the board
If you can spot a skyscraper, this is a comfortable setting: it is the single most common answer here by a wide margin. If you cannot, learn it before you print — the skyscraper guide is a shorter read than the one you already did for X-Wing, because the scan is the same with one corner missing.
The two skills are worth having together. A board that offers neither is rare; a board that offers one and hides the other is what "hard" actually feels like.
Printing notes
Print with candidate marks. Hard is the first setting where you will routinely need to compare candidate lists across a whole unit to see a fish or an elimination, and at 29 clues the grid is dense enough that holding the lists in your head is a losing game.
One or two puzzles per page. Skyscraper and XY-Wing both require you to trace two lines at once, and you will want margin space to mark the towers or the pivot next to the grid. Four-per-page works, but it turns pattern hunting into squinting.
If you want the harder half of this setting
Half of this sheet is practice for one technique you may not have met yet. If you want to drill only the technique the setting is named after, the X-Wing practice sheet filters every puzzle to need one — and it is a much smaller set of boards, for the reason in the table above.