Winning blow: knight to d5 (b4·5)
c9-16204naming 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 1700 ShuffleRating — for advanced tacticians.
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 f1, queen h1, rook c1 g1, knight b4, pawn c2 d2 f2 h2 a3 e3 f4 a7.
Black: king f6, queen h8, rook b6 g8, knight c6 d6, pawn b5 d5 h5 g6 c7 d7 f7.
13 white and 13 black pieces are on the board; the puzzle position arises after move 15.
The position in numbers
Black are ahead by 2 points of material (30 against 32; pawn = 1, knight and bishop = 3, rook = 5, queen = 9) — the tactic has to convert or outweigh that.
The white king stands on f1, the black king on f6.
It is White to move on move 15, with 37 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 8 pawns, Black 7. No file is fully open, so the heavy pieces have to be pried in. Half-open for White: b, g.
The White king has 5 empty squares to step to right now — the fewer they are, the closer a mating net.
Solution & explanation
Main line
15. Nxd5+ Kg7 16. Nxb6 cxb6 17. Qd5 Nc4 18. Qxd7
Why it works
- Great move! knight to d5 keeps the pressure (+3.7).
- Well found: knight to b6 (+3.8).
- Strong! queen to d5 is the sharp choice (+3.9).
- Best move. queen to d7 is exactly what the engine plays (+4.0).
- You win a piece — the rook.
- If instead Kg7, then Nxb6 and you win the rook.
Move by move
- 15. Nxd5+ — knight to d5 (capture) with check
- Kg7 — king to g7
- 16. Nxb6 — knight to b6 (capture)
- cxb6 — pawn to b6 (capture)
- 17. Qd5 — queen to d5
- Nc4 — knight to c4
- 18. Qxd7 — queen to d7 (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.
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 #177.
SP-177 · BastionGuard — King shifted to c or f, knights kept clear of the edges — 168 positions in all.
The king starts on f1, the rooks on c1 and g1, the queen on h1.
Castling short simply swaps the two pieces: the king on f1 and the rook on g1 trade places.
A bishop starts in the corner on a1: it has a single diagonal, which the b-pawn unlocks, running out to h8.
One second-rank pawn starts with no defender at all: a2.
The setup belongs to the BastionGuard family; read right to left it becomes position 779.
The engine's main line opens with g4.
Morozov Balance Index: 8 of 100 — class D — largest edge. Engine evaluation of the starting position: +45 centipawns for White (depth 44, 400 000 000 nodes).
Explore position #177Provenance
Mined from the project's engine self-play games.
Pack 013 · SP-177
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