GridWits
Extreme tier Technique 29 of 46 Reference only

Exocet

Two "base" cells constrain two "target" cells elsewhere on the board so tightly that the targets' candidates must come entirely from the base cells' digits.

The solver does not attempt this technique, so Smart Hint will never suggest it. It is documented because you may still want to spot it yourself.

How it works

  1. 1B2 and C2 — the base cells — share one row of the top-left box and hold exactly {2, 5, 8} between them.
  2. 2The two targets, E1 and H3, sit in the band's other two boxes, each in a different row from the base. Geometry elsewhere on the board is what proves they can only ever be filled from the base's digits.
  3. 3So any candidate at E1 or H3 outside {2, 5, 8} — the 9 and the 4 — goes at once. Recognising a valid Exocet is the hard part; the elimination is trivial once you have one.

Play a Sudoku that needs this technique →

A 1 B 2 C 3 D 4 E 5 F 6 G 7 H 8 I 9 2 5 8 9 2 5 8 2 5 8 2 4 5 8 2 5 8 2 5 8 9 4
  • Cells that establish the pattern
  • Where the conclusion lands
  • Candidate ruled out
Next in the ladder Death Blossom →

A "stem" cell's candidates are each matched to their own Almost Locked Set (a "petal") — a digit common to every petal can be eliminated from any cell all the petals can see.