Winning blow: knight to c6 (b4·9)
c9-23671naming 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 1200 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 c1, queen g2, rook a1, knight c3 b4, pawn b2 c2 a3 g3 f4.
Black: king b8, queen f8, rook a8, bishop g8, knight c5, pawn a5 f5 c6 g6 c7.
10 white and 10 black pieces are on the board; the puzzle position arises after move 21.
The position in numbers
Material is level — 25 points of pieces on each side (pawn = 1, knight and bishop = 3, rook = 5, queen = 9).
The white king stands on c1, the black king on b8.
It is White to move on move 21, with 34 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 5 pawns, Black 5. Files fully open (no pawns of either colour): d, e, h — natural highways for the rooks and queen.
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
21. Nxc6+ Kc8 22. O-O-O Nb7 23. g4 Ra6 24. gxf5
Why it works
- Great move! knight to c6 keeps the pressure (+5.0).
- king to c1 develops smoothly.
- Precise: pawn to g4 is the top choice (+4.8).
- Best move. pawn to f5 is exactly what the engine plays (+4.9).
- You reach a winning position (+4.9).
- If instead Kc8, then O-O-O and you stay on top.
Move by move
- 21. Nxc6+ — knight to c6 (capture) with check
- Kc8 — king to c8
- 22. O-O-O — king to a1
- Nb7 — knight to b7
- 23. g4 — pawn to g4
- Ra6 — rook to a6
- 24. gxf5 — pawn to f5 (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.
About this position
These pieces come from starting position #558.
SP-558 · BastionGuard — King off-centre on c or f with both knights on inner files.
The king starts on c1, the rooks on a1 and h1, the queen on e1.
The king already stands on c1, so castling long moves only the rook, from a1 to d1.
The bishops stand on f1 and g1; their long diagonals reach a6 and a7 once the e- and f-pawns step aside.
The pawn on c2 is defended by the king alone — the same soft spot f2 is in the classical setup.
The setup belongs to the BastionGuard family; read right to left it becomes position 500.
The engine's main line opens with e4, putting a pawn straight into the centre.
Morozov Balance Index: 75 of 100 — class B — balanced. Engine evaluation of the starting position: +19 centipawns for White (depth 46, 400 000 000 nodes).
Explore position #558Provenance
Mined from the project's engine self-play games.
Pack 008 · SP-558
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