How Koga decides
- We make a quiet (non-capturing) move that threatens an enemy piece which is currently guarding something important.
- The opponent saves the threatened piece by moving it away.
- By stepping aside, that piece stops guarding a square it used to cover. A later move in the line cashes in on that now-unguarded square — either checkmate, or a capture worth at least a minor piece.
- The threatening move must not itself be a capture — distraction is about luring a piece, not winning one outright.
- The square we cash in on must be a DIFFERENT square from the one the lured piece ran to. If the only thing we 'win' is the piece on its new square, that is just a forced trade, not a distraction.
- A piece does not guard the square it is standing on, so a capture on the retreat square never qualifies.
- The abandoned square must really become weak: after the piece leaves, our attackers on that square must match or outnumber the remaining defenders.
- Both motifs pull a defender off duty, and the two are closely related.
- Deflection forces the piece by a check or by a recapture it cannot refuse, and the square we then exploit is the very one the piece had been guarding.
- Distraction instead uses a quiet threat: the piece retreats to safety, and we strike a different square it can no longer cover.
- When both fit the same line, deflection takes priority — it is reported and distraction is suppressed.
Test positions (the examples that guard against regressions)
Bishop lures the knight off c4
A constructed position. Bf2 threatens the knight on b6, which is the only guard of the bishop on c4. The knight runs to d7, and Rxc4 then wins the now-undefended bishop on c4 — a square distinct from the knight's retreat.
Pawn lures the knight off d5
A constructed position. The pawn push g5 attacks the knight on f6, the only defender of the bishop on d5. The knight retreats to h5, and Rxd5 wins the bishop on the square it abandoned.
No distraction — only a forced queen trade
Lichess yqx800dr is not a puzzle id (it is a game/move reference), so no link. After f3 the black queen on g4 is attacked; its only retreat is e6, where Qxe6 simply trades queens. The square we land on is the queen's own retreat square, so this is a forced trade, not a distraction.
No distraction — king mated on its own retreat square
Lichess 000Zo. Re1+ forces the king to f2, and Rf1# mates it right there. The king is checkmated on the very square it fled to — there is no separate abandoned square being exploited, so this is a king hunt rather than a distraction.