Winning blow: knight to a6 (c5)
c9-12362naming tag (square·N)Opens in the app if installed, otherwise downloads the APK.
The tactical motive
Chess960 twist: use the unusual starting setup of the pieces.
Winning tactic: there is a move that gains a decisive advantage — find it.
Difficulty 1060 ShuffleRating — club-player level.
White to move — find the best continuation
How to recognize this tactic
In Chess960 the pieces start on unfamiliar squares, so tactics appear earlier and from unusual angles. Do not trust classical patterns — read the actual lines of the bishops, the rooks and the queen from where they really stand in this position.
This position hides a concrete tactic that wins material or mates. Start with the most forcing candidate moves — checks, captures and threats — and calculate each to a clear end before choosing; the winning line is usually the one the opponent cannot meet.
General method: before you move, list the forcing candidates — every check, every capture, every direct threat — and calculate those first. The solution to a tactic is almost always among them.
Position on the board
White: king c3, rook f5, bishop e3, knight c5, pawn d2 a4 g4.
Black: king c8, rook a6 g8, knight e1, pawn a5 b7.
7 white and 6 black pieces are on the board; the puzzle position arises after move 40.
The position in numbers
Black are ahead by 1 points of material (14 against 15; pawn = 1, knight and bishop = 3, rook = 5, queen = 9) — the tactic has to convert or outweigh that.
The white king stands on c3, the black king on c8.
It is White to move on move 40, with 31 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 3 pawns, Black 2. Files fully open (no pawns of either colour): c, e, f, h — natural highways for the rooks and queen. Half-open for White: b.
The White king has 4 empty squares to step to right now — the fewer they are, the closer a mating net.
Solution & explanation
Main line
40. Nxa6 bxa6 41. Bf2 Rxg4 42. Bxe1
Why it works
- Great move! knight to a6 keeps the pressure (+4.2).
- bishop to f2 develops smoothly.
- Precise: bishop to e1 is the top choice (+4.0).
- You win a piece — the rook.
- If instead bxa6, then Bf2 and you stay on top.
Move by move
- 40. Nxa6 — knight to a6 (capture)
- bxa6 — pawn to a6 (capture)
- 41. Bf2 — bishop to f2
- Rxg4 — rook to g4 (capture)
- 42. Bxe1 — bishop to e1 (capture)
Types in this puzzle
Winning blow
Find the strike that wins material by force.
A winning blow is a forced material gain that does not fit a single textbook motif. The general tactical recipe applies: spot loose pieces, an awkwardly placed king, overloaded lines. Go through the forcing moves in order of violence — checks, captures, threats — because most combinations start with one of them. Do not judge by feel: calculate the concrete line until the outcome is beyond doubt.
Endgame tactic
Tactics live in the endgame too — strike while material is scarce.
Tactics do not retire when the queens come off: forks, pins and double attacks live on in the endgame. With so little material left, every tactical loss is almost always decisive. The signs are the usual ones — undefended pieces, king and piece on one line, a pawn about to promote. Even in a "technical" ending, scan for a shot before every move, both yours and your opponent's.
About this position
These pieces come from starting position #698.
SP-698 · BastionGuard — A c- or f-file king and two knights on inner files (b–g).
The king starts on c1, the rooks on a1 and h1, the queen on b1.
The king already stands on c1, so castling long moves only the rook, from a1 to d1.
The bishops stand on e1 and f1; their long diagonals reach a5 and a6 once the d- and e-pawns step aside.
Every pawn on the second rank is defended from the very first move.
The setup belongs to the BastionGuard family; read right to left it becomes position 453.
The engine's main line opens with c3.
Morozov Balance Index: 65 of 100 — class B — balanced. Engine evaluation of the starting position: +22 centipawns for White (depth 43, 400 000 000 nodes).
Explore position #698Provenance
Mined from the project's engine self-play games.
Pack 006 · SP-698
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