How Koga decides
- Attraction is read across the engine's main line, not from a single move. It needs at least three plies.
- First we move a piece to a square; the opponent captures there, so an enemy piece is drawn (lured) onto that square.
- Then a follow-up move punishes the lured piece on its new square — a check or attack on it, a capture of material it used to guard, a pin, a skewer through it, or a mate it helps deliver.
- The lured piece must be worth more than a pawn: pawns are too cheap to be meaningful decoy targets.
- The bait — our piece that lands on the square, inviting the capture.
- The lured piece — the enemy piece that captures and is now stuck on the worse square.
- The exploit — our next move that profits specifically because the lured piece is now where we wanted it.
- Mere recapture — if the follow-up just takes back on the same square the opponent captured on, that is an even trade, not a decoy.
- The exploit must really pay. An attack on the lured piece counts only if grabbing it would not lose material to its defenders; otherwise the move's true point lies elsewhere.
- The luring must matter. We mentally put the lured piece back on its old square: if the exploit would work just as well from there, the piece was not actually decoyed and we do not call it attraction.
Test positions (the examples that guard against regressions)
A fork, not a decoy
Lichess 00Rcs. The knight goes f5–g3, checking the king on e4 and hitting the rook on h1 at the same time. The king steps to f4, then Nxh1 wins the rook. But the knight already attacked h1 from g3 before the king moved, so the king's flight did not enable the capture — this is a plain fork, not an attraction.
Clearance, not a decoy
From a real game: 12.Nxe5 vacates f3 so the queen can reach h5, and the main line runs Nxe5 c6xe5 Qh5 g6 Qxh3. The queen on h5 does rake the 5th rank and incidentally eyes the recapturer on e5, but Qxe5 would simply hang the queen to the f6 pawn. The genuine threat is Qxh3 down the h-file, so this is clearance, not a lure of the e5 piece.
Golden puzzles — every real Lichess puzzle Koga is tested against for this tactic (8)
Lichess 01MpA
Lichess 01MpA (rating 1567). Solution: Rxa1 Rxa1 Rb1+ Kg2 Rxa1.
Lichess 00H87
Lichess 00H87 (rating 1958). Solution: Qc8+ Kh7 Rxf7+ Ng7 Rxg7+ Kxh6 Qh8+ Kg5 Rxg6+ Kxg6 Qg8+ Kf6 Qxg3.
Koga flags decoy as a follow-up here — it fires later in the line, on Rxg6+, not on the move shown above.
Lichess 010MJ
Lichess 010MJ (rating 1658). Solution: Rxg7+ Kh8 Rh7+ Kxh7 Rxf7+ Kh8 Qg7#.
Koga flags decoy as a follow-up here — it fires later in the line, on Rh7+, not on the move shown above.
Lichess 02a72
Lichess 02a72 (rating 1741). Solution: Rxf1+ Kxf1 Qf2#.
Lichess 02dlS
Lichess 02dlS (rating 2183). Solution: Rxg6 Qxd4 Rxg7+ Kxg7 Qxh6+.
Koga flags decoy as a follow-up here — it fires later in the line, on Rxg7+, not on the move shown above.
Lichess 00cRN
Lichess 00cRN (rating 1726). Solution: Rxg7+ Kxg7 f6+ Kf7 fxe7.
Lichess 00BrZ
Lichess 00BrZ (rating 1382). Solution: Rxh2+ Kxh2 Rh8+ Qh6 Rxh6#.
Lichess 019gx
Lichess 019gx (rating 2104). Solution: Ra4+ Kxa4 Ra8+ Ra7 Rxa7#.