Attack on the uncastled king: knight to d5 (c3·23)
c9-10176naming 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.
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.
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 c1, queen g3, rook b1 e1, bishop f1, knight c3, pawn c2 d2 g2 a4 b4 h4.
Black: king c8, queen h8, rook b7 e8, bishop a8, knight d5 d8, pawn e4 b5 g6 c7 d7.
12 white and 12 black pieces are on the board; the puzzle position arises after move 17.
The position in numbers
Black are ahead by 2 points of material (31 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 c1, the black king on c8.
It is White to move on move 17, with 38 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
17. Nxd5 Ra7 18. Qf2 Rxa4 19. Bxb5 Ra2 20. Nc3
Why it works
- Great move! knight to d5 keeps the pressure (+2.8).
- Spot on — queen to f2 (+2.6).
- Precise: bishop to b5 is the top choice (+2.7).
- Best move. knight to c3 is exactly what the engine plays (+3.2).
- You win a piece — the knight.
- If instead Ra7, then Qf2 and you win the knight.
Move by move
- 17. Nxd5 — knight to d5 (capture)
- Ra7 — rook to a7
- 18. Qf2 — queen to f2
- Rxa4 — rook to a4 (capture)
- 19. Bxb5 — bishop to b5 (capture)
- Ra2 — rook to a2
- 20. Nc3 — knight to c3
Types in this puzzle
Winning blow
Find the strike that wins material by force.
A winning blow is a forced material gain that does not fit a single textbook motif. The general tactical recipe applies: spot loose pieces, an awkwardly placed king, overloaded lines. Go through the forcing moves in order of violence — checks, captures, threats — because most combinations start with one of them. Do not judge by feel: calculate the concrete line until the outcome is beyond doubt.
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.
Uncastled king
The king lingered in the middle — punish the delay.
Punishing the uncastled king: your opponent delayed castling, and now his king is stuck on its starting square under fire. In Chess960 this is deadlier than in classical chess — the king may start in the center or near the edge, and the familiar defensive setups simply do not apply. The signs: the victim still holds castling rights, and the files toward his king are half-open. Open lines before the king manages to hide.
About this position
These pieces come from starting position #850.
SP-850 · BastionGuard — Both knights begin inside the board while the king stands on c or f; a position and its mirror twin share this family.
The king starts on c1, the rooks on b1 and e1, the queen on h1.
The king already stands on c1, so castling long moves only the rook, from b1 to d1.
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 103.
The engine's main line opens with e4, putting a pawn straight into the centre.
Morozov Balance Index: 31 of 100 — class C — noticeable edge. Engine evaluation of the starting position: +32 centipawns for White (depth 43, 400 000 000 nodes).
Explore position #850Provenance
Mined from the project's engine self-play games.
Pack 007 · SP-850
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