Winning blow: queen to a7 (a4·2)
c9-11471naming 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.
Winning tactic: there is a move that gains a decisive advantage — find it.
Difficulty 1430 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.
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 d1, queen a4, rook e1, bishop h1, knight b5, pawn a2 d2 e2 h2 b3 g3.
Black: king b8, queen f8, rook d8 e8, bishop f4 a8, pawn b6 c6 e6 c7 h7.
11 white and 11 black pieces are on the board; the puzzle position arises after move 18.
The position in numbers
Black are ahead by 4 points of material (26 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 d1, the black king on b8.
It is White to move on move 18, with 36 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 6 pawns, Black 5. Files fully open (no pawns of either colour): f — natural highways for the rooks and queen. Half-open for White: c.
Black hold the bishop pair, an edge in open lines. 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
18. Qa7+ Kc8 19. Qxa8+ Kd7 20. Qxc6+ Ke7 21. gxf4
Why it works
- Great move! queen to a7 keeps the pressure (+4.8).
- Well found: queen to a8 (+4.8).
- Strong! queen to c6 is the sharp choice (+4.8).
- Best move. pawn to f4 is exactly what the engine plays (+4.7).
- You win a piece — the bishop.
- If instead Kc8, then Qxa8+ and you win the bishop.
Move by move
- 18. Qa7+ — queen to a7 with check
- Kc8 — king to c8
- 19. Qxa8+ — queen to a8 (capture) with check
- Kd7 — king to d7
- 20. Qxc6+ — queen to c6 (capture) with check
- Ke7 — king to e7
- 21. gxf4 — pawn to f4 (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.
Remove the defender
Capture the guard first — then take what it protected.
Removing the defender is the straightforward plan: capture the guard first, then take what it guarded. Unlike deflection, the defender is not lured away — it is traded off or destroyed on the spot. Stare at the target you crave and ask who defends it, and whether that defender can be profitably eaten. Count the whole capture sequence, not just the first move — the trade must pay off at the end.
About this position
These pieces come from starting position #355.
SP-355 · ThroneGuard — A central king (d or e) and two knights tucked onto inner files: the family that holds the standard array, SP-518.
The king starts on d1, the rooks on c1 and e1, the queen on f1.
Castling long simply swaps the two pieces: the king on d1 and the rook on c1 trade places.
A bishop starts in the corner on a1: it has a single diagonal, which the b-pawn unlocks, running out to h8.
The second rank carries 2 pawns with no defender at all: a2, h2.
The setup belongs to the ThroneGuard family; read right to left it becomes position 307.
The engine's main line opens with g4.
Morozov Balance Index: 65 of 100 — class B — balanced. Engine evaluation of the starting position: +22 centipawns for White (depth 44, 400 000 000 nodes).
Explore position #355Provenance
Mined from the project's engine self-play games.
Pack 010 · SP-355
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