Winning blow: queen to b7 (f3·2)
c9-14903naming 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 1010 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 f3, rook c1 d1, bishop g2, knight f4, pawn f2 c3 d3 d4 h5.
Black: king a7, queen c8, rook b7, bishop b3, pawn c4 a5 h6 g7.
11 white and 8 black pieces are on the board; the puzzle position arises after move 39.
The position in numbers
White are ahead by 9 points of material (30 against 21; 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 a7.
It is White to move on move 39, with 27 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 5 pawns, Black 4. Files fully open (no pawns of either colour): b, e — natural highways for the rooks and queen. Half-open for White: a, g.
The White king has 2 empty squares to step to right now — the fewer they are, the closer a mating net.
Solution & explanation
Main line
39. Qxb7+ Qxb7 40. Bxb7 a4 41. dxc4
Why it works
- Great move! queen to b7 keeps the pressure (+8.6).
- Well found: bishop to b7 (+8.6).
- Precise: pawn to c4 is the top choice (+8.7).
- You win a piece — the queen.
- If instead Qxb7, then Bxb7 and you win the queen.
Move by move
- 39. Qxb7+ — queen to b7 (capture) with check
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.
About this position
These pieces come from starting position #858.
SP-858 · RampartGuard — King on the wing (b/g) with both knights on inner files.
The king starts on b1, the rooks on a1 and d1, the queen on h1.
From b1 the king makes the longest journey Chess960 allows when castling short: five squares to g1.
The bishops stand on e1 and f1; their long diagonals reach a5 and a6 once the d- and e-pawns step aside.
The pawn on b2, c2 is defended by the king alone — the same soft spot f2 is in the classical setup.
The setup belongs to the RampartGuard family; read right to left it becomes position 101.
The engine's main line opens with e4, putting a pawn straight into the centre.
Morozov Balance Index: 24 of 100 — class D — largest edge. Engine evaluation of the starting position: +35 centipawns for White (depth 44, 400 000 000 nodes).
Explore position #858Provenance
Mined from the project's engine self-play games.
Pack 006 · SP-858
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