Winning blow: queen to a6 (b7·3)
c9-17162naming 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 1110 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 c2, queen b7, rook a1 h1, bishop d3, knight d4, pawn a2 d2 c3 b4 e4 h4 f5.
Black: king e8, queen h6, rook b8 h8, bishop e5, knight c8, pawn a4 c6 d7 e7 h7.
13 white and 11 black pieces are on the board; the puzzle position arises after move 19.
The position in numbers
White are ahead by 2 points of material (32 against 30; pawn = 1, knight and bishop = 3, rook = 5, queen = 9) — the tactic has to convert or outweigh that.
The white king stands on c2, the black king on e8.
It is White to move on move 19, with 44 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 7 pawns, Black 5. Files fully open (no pawns of either colour): g — 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
19. Qa6 Bxd4 20. cxd4
Why it works
- Great move! queen to a6 keeps the pressure (+2.8).
- Well found: pawn to d4 (+3.0).
- You reach a winning position (+3.0).
- If instead Bxd4, then cxd4 and you stay on top.
Move by move
- 19. Qa6 — queen to a6
- Bxd4 — bishop to d4 (capture)
- 20. cxd4 — pawn to d4 (capture)
Types in this puzzle
Quiet move
No check, no capture — yet this modest move decides the game.
A quiet move gives no check and takes nothing — yet it decides the game by creating an unstoppable threat or stealing the king's last square. This is the hardest class of moves: the eye hunts for loud blows while a modest shift does the winning. The clue: every forcing try runs into a defense, so seek the move that strengthens the threat or takes squares away. Train yourself to ask: what if I neither capture nor check, but quietly improve?
About this position
These pieces come from starting position #636.
SP-636 · ThroneScout — King on a central file (d/e) with a knight starting on the rim (a/h).
The king starts on d1, the rooks on a1 and f1, the queen on e1.
The kingside rook already stands on f1, so castling short moves only the king, from d1 to g1.
The bishops stand on b1 and g1; their long diagonals reach h7 and a7 once the c- and f-pawns step aside.
The second rank carries 2 pawns with no defender at all: b2, g2.
The setup belongs to the ThroneScout family; read right to left it becomes position 236.
The engine's main line opens with f4.
Morozov Balance Index: 20 of 100 — class D — largest edge. Engine evaluation of the starting position: +37 centipawns for White (depth 47, 400 000 000 nodes).
Explore position #636Provenance
Mined from the project's engine self-play games.
Pack 007 · SP-636
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