Winning blow: king to a2 (a3·3)
c9-12628naming 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 a3, queen h4, rook h5, bishop e4, knight g4, pawn d2 e3.
Black: king f7, queen g7, rook c8, bishop a8, knight d8, pawn a2 a6 d6 b7 d7.
7 white and 10 black pieces are on the board; the puzzle position arises after move 28.
The position in numbers
Black are ahead by 3 points of material (22 against 25; pawn = 1, knight and bishop = 3, rook = 5, queen = 9) — the tactic has to convert or outweigh that.
The white king stands on a3, the black king on f7.
It is White to move on move 28, with 43 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 2 pawns, Black 5. Files fully open (no pawns of either colour): c, f, g, h — natural highways for the rooks and queen. Half-open for White: a, 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
28. Kxa2 d5 29. Rh7 Ke6 30. Rxg7
Why it works
- Best move. king to a2 is exactly what the engine plays (+7.5).
- Well found: rook to h7 (+9.6).
- Precise: rook to g7 is the top choice (+10.5).
- You win a piece — the queen.
- If instead d5, then Rh7 and you stay on top.
Move by move
- 28. Kxa2 — king to a2 (capture)
- d5 — pawn to d5
- 29. Rh7 — rook to h7
- Ke6 — king to e6
- 30. Rxg7 — rook to g7 (capture)
Types in this puzzle
Absolute pin
A piece is pinned against its king — it cannot legally move.
An absolute pin freezes a piece on the line between its own king and your long-range attacker: moving it is simply illegal. The pattern is three units on one straight line — your bishop, rook or queen, an enemy piece, and the enemy king behind it. A pinned piece neither attacks nor defends anything: treat it as if it were off the board. Pile up on it, ideally with a pawn, because running away is against the rules.
Queen trap
The strongest piece ventures too far — and cannot come back.
A queen trap catches the strongest piece after it ventures too far and finds no way home. The usual story is a queen grabbing a distant pawn — the classic poisoned pawn. The warning signs: the queen has few retreat squares, and enemy minor pieces cut them off one by one, gaining tempo with every move. Before your queen snacks on a pawn in enemy territory, count her escape routes — fewer than two means stay home.
About this position
These pieces come from starting position #640.
SP-640 · ThroneScout — A knight starts on the edge (a/h) and the king sits centrally on d or e; the mirror twin stays in this family too.
The king starts on e1, the rooks on c1 and f1, the queen on g1.
The kingside rook already stands on f1, so castling short moves only the king, from e1 to g1.
A bishop starts in the corner on a1: it has a single diagonal, which the b-pawn unlocks, running out to h8.
The pawn on d2, e2 is defended by the king alone — the same soft spot f2 is in the classical setup.
The setup belongs to the ThroneScout family; read right to left it becomes position 223.
The engine's main line opens with c4.
Morozov Balance Index: 65 of 100 — class B — balanced. Engine evaluation of the starting position: +22 centipawns for White (depth 45, 400 000 000 nodes).
Explore position #640Provenance
Mined from the project's engine self-play games.
Pack 006 · SP-640
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