Winning blow: knight to d7 (b6·2)
c9-28013naming 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 1200 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 e6, rook d1, knight b6, pawn b2 c2 a4.
Black: king b8, queen h2, rook a7 f8, knight d7, pawn a5 c5.
7 white and 7 black pieces are on the board; the puzzle position arises after move 37.
The position in numbers
Black are ahead by 4 points of material (20 against 24; 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 b8.
It is White to move on move 37, with 45 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 3 pawns, Black 2. Files fully open (no pawns of either colour): d, e, f, g, h — natural highways for the rooks and queen.
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
37. Nxd7+ Rxd7 38. Qxd7 Qc7 39. Qb5+ Qb7 40. Qxc5
Why it works
- Great move! knight to d7 keeps the pressure (+5.2).
- Well found: queen to d7 (+5.5).
- Strong! queen to b5 is the sharp choice (+5.3).
- Best move. queen to c5 is exactly what the engine plays (+5.3).
- You win a piece — the rook.
- If instead Rxd7, then Qxd7 and you win the rook.
Move by move
- 37. Nxd7+ — knight to d7 (capture) with check
- Rxd7 — rook to d7 (capture)
- 38. Qxd7 — queen to d7 (capture)
- Qc7 — queen to c7
- 39. Qb5+ — queen to b5 with check
- Qb7 — queen to b7
- 40. Qxc5 — queen to c5 (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.
Winning exchange
A forced series of captures on one square ends in your favour.
A winning exchange is a forced series of captures on one square that leaves you ahead in material. It is pure arithmetic: count the attackers and defenders of the square and note the value of every piece in the queue. Capture in the right order — cheap pieces first, expensive ones later — or a winning trade turns into a losing one. The classic error is stopping the count halfway and missing the opponent's final recapture.
About this position
These pieces come from starting position #717.
SP-717 · RampartGuard — King pushed to the b- or g-file, knights off the edges — 144 positions here.
The king starts on b1, the rooks on a1 and h1, the queen on c1.
From b1 the king makes the longest journey Chess960 allows when castling short: five squares to g1.
The bishops stand on d1 and g1; their long diagonals reach h5 and a7 once the e- and f-pawns step aside.
Every pawn on the second rank is defended from the very first move.
The setup belongs to the RampartGuard family; read right to left it becomes position 440.
The engine's main line opens with a4.
Morozov Balance Index: 18 of 100 — class D — largest edge. Engine evaluation of the starting position: +38 centipawns for White (depth 45, 400 000 000 nodes).
Explore position #717Provenance
Mined from the project's engine self-play games.
Pack 008 · SP-717
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