- In the highlighted lines, 3 fits only in the highlighted cells.
- Whichever cells take 3, each crossing line gets one of them.
- So 3 can go nowhere else in the lines that cross them.
Finned X-Wing in sudoku
A Finned X-Wing is an X-Wing in which one of the two rows has an extra cell or two for the number, next to one corner and in the same box as it. The extra cells are the fin. The pattern removes less than a clean X-Wing: only the cells of the X-Wing columns that also lie in the box of the fin lose the number.
Or scan with your phone
How to spot it
Look for an X-Wing that almost works: two rows, two columns, and one or two cells too many in one of the rows, all in the box of one corner. Then look in that box, in the column of that corner, for notes of the number.
Why it works
Either one of the fin cells holds the number, or none does and the X-Wing is a real one. A cell that sits in the box of the fin and in an X-Wing column loses the number in both cases: the fin shares its box, and the X-Wing fills its column.
On a real puzzle
This is Finned X-Wing on its practice puzzle, at the first step that needs it. The game's hint explains the step like this:
Practice it
No level of the game needs Finned X-Wing, so this practice puzzle is harder than Extreme, its hardest level. Fill in what you can, then look for the pattern, or ask for the hint: each game has one.