Winning blow: knight to d6 (f5·8)
c9-11445naming 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 1060 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 g1, queen g2, rook d1 f1, bishop a1, knight f5, pawn a2 g3 c4 h4.
Black: king h7, queen f7, rook c8 f8, bishop d6, knight d3, pawn b4 d5 e5 h5 b6 f6 a7 g7.
10 white and 14 black pieces are on the board; the puzzle position arises after move 19.
The position in numbers
Black are ahead by 4 points of material (29 against 33; pawn = 1, knight and bishop = 3, rook = 5, queen = 9) — the tactic has to convert or outweigh that.
The white king stands on g1, the black king on h7.
It is White to move on move 19, with 37 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 4 pawns, Black 8. No file is fully open, so the heavy pieces have to be pried in. Half-open for White: b, d, e, f.
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
19. Nxd6 Qg6 20. Nxc8 Rxc8 21. cxd5
Why it works
- Great move! knight to d6 keeps the pressure (+2.6).
- A brilliant blow: knight to c8, and you stand better (+2.5).
- Strong! pawn to d5 is the sharp choice (+2.4).
- You win a piece — the rook.
- If instead Qg6, then Nxc8 and you win the rook.
Move by move
- 19. Nxd6 — knight to d6 (capture)
- Qg6 — queen to g6
- 20. Nxc8 — knight to c8 (capture)
- Rxc8 — rook to c8 (capture)
- 21. cxd5 — pawn to d5 (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.
Knight fork
One knight move attacks two targets at once — the opponent can only save one.
A fork is one move that attacks two targets at once, and no piece forks better than the knight. Look through the knight's eyes: it jumps in an L and never moves along straight lines, which is exactly why its threats get missed. Both victims of a knight fork always stand on squares of one color, while the knight strikes from the opposite color. Hunt for the square from which the knight hits the king and a heavy piece at once.
About this position
These pieces come from starting position #432.
SP-432 · RampartGuard — King on the wing (b/g) with both knights on inner files.
The king starts on g1, the rooks on c1 and h1, the queen on f1.
The king already stands on its castled square, so castling short moves only the rook, from h1 to f1.
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: d2.
The setup belongs to the RampartGuard family; read right to left it becomes position 719.
The engine's main line opens with d4, putting a pawn straight into the centre.
Morozov Balance Index: 95 of 100 — class A — most balanced. Engine evaluation of the starting position: +3 centipawns for White (depth 46, 400 000 000 nodes).
In 50 self-play games White scored 54.0% (95% CI 40.4–67.0%).
Explore position #432Provenance
Mined from the project's engine self-play games.
Pack 006 · SP-432
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