Attack on the uncastled king: queen to a6 (f1·7)
c9-25850naming 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.
A fork made possible by the Chess960 piece placement.
Uncastled king: the enemy king is stuck in the centre — punish it before it castles.
Winning tactic: there is a move that gains a decisive advantage — find it.
Difficulty 1250 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.
A set-up fork needs one preparing move before the fork lands — a check that drives the king onto the forking square, or a capture that lines the targets up. Find the preparation first, then the fork it makes possible.
An uncastled king in the centre is a standing target. Look for ways to open the central files and diagonals against it with checks and threats before it can shelter — every tempo the king spends in the middle is a chance for a combination.
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 b1, queen f1, rook d1, bishop g1, knight e1 c5, pawn b2 c2 f2 h2 d4 e5.
Black: king c8, queen f7, rook b7 d8, bishop h8, knight b6 e8, pawn e6 g6 a7 c7 d7.
12 white and 12 black pieces are on the board; the puzzle position arises after move 11.
The position in numbers
Black are ahead by 4 points of material (29 against 33; pawn = 1, knight and bishop = 3, rook = 5, queen = 9) — the tactic has to convert or outweigh that.
The white king stands on b1, the black king on c8.
It is White to move on move 11, with 33 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 6 pawns, Black 5. No file is fully open, so the heavy pieces have to be pried in. Half-open for White: a, g.
The White king has 3 empty squares to step to right now — the fewer they are, the closer a mating net.
Solution & explanation
Main line
11. Qa6 Nd6 12. exd6 O-O 13. Qxb7
Why it works
- Great move! queen to a6 keeps the pressure (+3.7).
- Well found: pawn to d6 (+3.7).
- Precise: queen to b7 is the top choice (+3.9).
- You win a piece — the rook.
- If instead Nd6, then exd6 and you win the knight.
Move by move
- 11. Qa6 — queen to a6
- Nd6 — knight to d6
- 12. exd6 — pawn to d6 (capture)
- O-O — king to d8
- 13. Qxb7 — queen to b7 (capture)
Types in this puzzle
Setup fork
The random setup allows a fork that classical chess never sees.
A setup fork is a double attack that exists only because of the unusual starting squares — in classical chess these targets never stand side by side. Look for pairs of undefended pieces on your opponent's back rank and for squares from which a knight or pawn hits both at once. Such forks usually appear within the first moves, before the pieces disperse. In every new position, note right away which starting pieces are defended by no one.
Only move
Everything else loses — find the only move that holds.
An only move is a position where everything loses except one single continuation. You cannot play "by hand" here: run through fundamentally different defenses — run away, block, trade, counterattack — and discard the ones that fail. The hallmark of these puzzles is that the obvious moves lose quickly while the solution often looks strange. First understand exactly what the threat is — then the one saving move reveals itself.
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.
About this position
These pieces come from starting position #383.
SP-383 · BastionScout — King shifted to c or f, with a knight committed to the corner from move one.
The king starts on c1, the rooks on b1 and d1, the queen on f1.
The king already stands on c1, so castling long moves only the rook, from b1 to d1.
A bishop starts in the corner on h1: it has a single diagonal, which the g-pawn unlocks, running out to a8.
One second-rank pawn starts with no defender at all: a2.
The setup belongs to the BastionScout family; read right to left it becomes position 288.
The engine's main line opens with f4.
Morozov Balance Index: 26 of 100 — class C — noticeable edge. Engine evaluation of the starting position: +34 centipawns for White (depth 46, 400 000 000 nodes).
Explore position #383Provenance
Mined from the project's engine self-play games.
Pack 009 · SP-383
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