Attack on the uncastled king: knight to d5 (f4·4)
c9-26616naming 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.
Uncastled king: the enemy king is stuck in the centre — punish it before it castles.
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.
An uncastled king in the centre is a standing target. Look for ways to open the central files and diagonals against it with checks and threats before it can shelter — every tempo the king spends in the middle is a chance for a combination.
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 g3, rook e2 b3, knight f4, pawn b2 c2 h3 a4 d4 g4.
Black: king b8, queen f6, rook c7 a8, bishop d7, knight c4, pawn a5 d5 h6 b7 e7.
11 white and 11 black pieces are on the board; the puzzle position arises after move 29.
The position in numbers
Black are ahead by 2 points of material (28 against 30; 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 29, with 41 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 6 pawns, Black 5. Files fully open (no pawns of either colour): f — natural highways for the rooks and queen. Half-open for White: e.
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
29. Nxd5 Qd6 30. Qxd6 Nxd6 31. Rxe7 O-O-O 32. Nxc7
Why it works
- Great move! knight to d5 keeps the pressure (+3.7).
- Spot on — queen to d6 (+3.5).
- Precise: rook to e7 is the top choice (+3.6).
- Best move. knight to c7 is exactly what the engine plays (+3.8).
- You win a piece — the queen.
- If instead Qd6, then Qxd6 and you win the queen.
Move by move
- 29. Nxd5 — knight to d5 (capture)
- Qd6 — queen to d6
- 30. Qxd6 — queen to d6 (capture)
- Nxd6 — knight to d6 (capture)
- 31. Rxe7 — rook to e7 (capture)
- O-O-O — king to a8
- 32. Nxc7 — knight to c7 (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 #806.
SP-806 · RampartScout — The king starts on b or g while a knight begins on the a- or h-file — the smallest family.
The king starts on b1, the rooks on a1 and g1, the queen on d1.
From b1 the king makes the longest journey Chess960 allows when castling short: five squares to g1.
The bishops stand on c1 and f1; their long diagonals reach h6 and a6 once the d- and e-pawns step aside.
One second-rank pawn starts with no defender at all: h2.
The setup belongs to the RampartScout family; read right to left it becomes position 150.
The engine's main line opens with a4.
Morozov Balance Index: 47 of 100 — class C — noticeable edge. Engine evaluation of the starting position: +27 centipawns for White (depth 44, 400 000 000 nodes).
Explore position #806Provenance
Mined from the project's engine self-play games.
Pack 008 · SP-806
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