Winning blow: queen to d7 (d6·5)
c9-10211naming 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 b1, queen d6, bishop f3, knight a4 e5, pawn g3 f4.
Black: king c8, queen d2, knight c7 d8, pawn c4 d5 f5 e6 a7.
7 white and 9 black pieces are on the board; the puzzle position arises after move 37.
The position in numbers
Material is level — 20 points of pieces on each side (pawn = 1, knight and bishop = 3, rook = 5, queen = 9).
The white king stands on b1, the black king on c8.
It is White to move on move 37, with 34 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): b, h — natural highways for the rooks and queen. Half-open for White: a, c, d, e.
The White king has 1 empty squares to step to right now — the fewer they are, the closer a mating net.
Solution & explanation
Main line
37. Qd7+ Kb7 38. Nc5+ Kb6 39. Nxc4+ dxc4 40. Qxd2
Why it works
- Great move! queen to d7 keeps the pressure (+7.2).
- Well found: knight to c5 (+8.4).
- Precise: knight to c4 is the top choice (+9.2).
- Best move. queen to d2 is exactly what the engine plays (+7.8).
- You win a piece — the queen.
- If instead Kb7, then Nc5+ and you stay on top.
Move by move
- 37. Qd7+ — queen to d7 with check
- Kb7 — king to b7
- 38. Nc5+ — knight to c5 with check
- Kb6 — king to b6
- 39. Nxc4+ — knight to c4 (capture) with check
- dxc4 — pawn to c4 (capture)
- 40. Qxd2 — queen to d2 (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.
Royal fork
A fork with check: the king must move, and the second piece is lost.
A royal fork is a fork with check — one of the two targets is the king itself. The check must be answered first, so nobody is left to rescue the second piece. Look for squares where your piece gives check and simultaneously attacks an undefended queen or rook. It is the most reliable fork of all, because your opponent literally has no choice.
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 #555.
SP-555 · BastionGuard — King shifted to c or f, knights kept clear of the edges — 168 positions in all.
The king starts on c1, the rooks on a1 and g1, the queen on f1.
The king already stands on c1, so castling long moves only the rook, from a1 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: h2.
The setup belongs to the BastionGuard family; read right to left it becomes position 497.
The engine's main line opens with g4.
Morozov Balance Index: 51 of 100 — class B — balanced. Engine evaluation of the starting position: +26 centipawns for White (depth 47, 400 000 000 nodes).
Explore position #555Provenance
Mined from the project's engine self-play games.
Pack 010 · SP-555
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