Variant Sudoku

X-Wing

When a digit fits in exactly two cells in each of two rows, and those cells line up in the same two columns, no other cell in those columns can hold that digit.

Practice now
9
2
9
3
9
6
9
9
7
9
4
2
8
3
9
8
3
9
1
6
9
5
2
7
2
3
4
9
1
6
9
1
5
6
7
3
4
2
8
2
9
1
7
5
3
9
1
9
2
6
3
8
3
7
9
4
1
9
2
6
5
2
6
3
1
9
So clear 9 from the rest of both columns.

Why it works

On the board above:

Row 3 has only two spots for 9: r3c3 and r3c6. Row 8 does too: r8c3 and r8c6. The four spots make the corners of a rectangle.

If the 9 in row 3 goes in column 3, the 9 in row 8 can’t also go in column 3, so it goes in column 6. And the other way round.

Either way, columns 3 and 6 each get their 9 from these corners. So no other cell in those columns can be 9. Remove it from r1c6.

How to spot it

  1. Pick one digit

    Look only at that digit’s spots. The digit filter under the board helps.

  2. Find two rows with exactly two spots

    Skip rows where the digit has three or more places to go.

  3. Check if the columns line up

    The four spots should make the corners of a rectangle.

  4. Clear the two columns

    Remove the digit from every other cell in those columns.

Practice

Real boards from the solver, with every pencil mark filled in. Spot it, then use it, then find it cold.

Loading the boards…

Try it in a real puzzle

Each of these needs an X-Wing to finish. It opens in the player.

Tips

Columns work too

Two columns with two spots each, lined up in the same two rows, clear those two rows instead.

No diagonal needed

The name comes from the X you can draw between the corners. The corners are what matter.

SkyscraperTwo rows with two spots each share one column. Whatever sees both of the other ends loses the digit.Next: Skyscraper →

In the glossary

X-wing