A Finned X-Wing is an almost-perfect X-Wing. Three corners are clean, but one line has an extra candidate — the fin — in the same box as a corner.
Fins shrink the elimination zone versus a perfect fish.
Before this: Learn X-Wing first.
Why it works
Two stories:
• If the fin is false, you have a perfect X-Wing and can clear certain cells. • If the fin is true, the digit is in the fin’s box/line instead — which still attacks some of the same cells.
Only cells hit in both stories (perfect fish OR fin true) are safe eliminations — the cover cells of the fin. Cells only hit by the perfect fish are not cleared.
Demonstration
Spot an X-Wing that is almost clean, with one extra fin candidate in a box.
The green cells are a Finned X-Wing on 3. Either the fish is real, or the fin is true.
Both stories attack the same cover cells near the fin — but not the full X-Wing elimination zone.
Eliminate 3 only from cells covered by the fin (red). Fish OR fin — only shared victims.
Example 1
Find an X-Wing with a single fin in one box.
This Finned X-Wing is on 1.
Remove 1 from the fin’s cover cells (red). Only eliminations that survive both fish and fin stories are valid.
Example 2
Find an X-Wing with a single fin in one box.
This Finned X-Wing is on 4.
Remove 4 from the fin’s cover cells (red). Only eliminations that survive both fish and fin stories are valid.