Expert technique

X-Wing: How to Spot It and What to Rule Out

Also written X Wing or XWing.

Follow one color into two rows that each have only two cells left for it, in the same two columns. The four cells make a rectangle, and that rectangle takes both columns.

A board with nothing left to place

BEFORE

This is what a stuck board looks like. Every open cell is noted, not one of them shows a single color, and no color has just one place left anywhere. There is far too much here to read at once, and that is the clue. Stop reading cells and pick a color.

Look at one color

Same board, but only the Orange dots are showing. Nothing has been erased, we are just looking at one color at a time. Thirteen cells can still take it, and now they are easy to count.

Two rows that match

Two of those rows have only two cells left for Orange, and it is the same two columns both times. Those four cells make a rectangle. One row takes the left column and the other takes the right, or the other way around. There is no third way to fill it.

Both columns are taken

Either way it settles, one of those columns gets its Orange from the top corner and the other gets it from the bottom corner. Both columns are used up. So every other cell in those two columns loses Orange, all the way down the board.

Read what that opened

AFTER

Look along the bottom row. Orange had two cells it could go in, and one of them sat in a locked column and just lost it. Only one cell is left, so place Orange there. The X did not solve anything by itself. It cleared enough room for a much simpler technique to finish the job.

Cells being readColor tints match the color being followed

Key Insight

An X Wing almost never places a bubble by itself, and that is normal. What it does is take a color out of cells nothing simpler could reach, and the answer appears a move later somewhere else. Look for it when the board stalls. Pick a color, find the rows where it only fits two cells, and check whether any two of those rows use the same two columns. It works exactly the same read down the columns instead of across the rows.

If you’re stuck on a puzzle, see what to try next, in order.