Attack on the uncastled king: pawn to d5 (c4·115)
c9-24618naming 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 e1, queen g1, rook c1 f1, bishop a3, knight a1 d1, pawn a2 d2 e2 h2 b3 c4 f4 g4.
Black: king e8, queen g8, rook b8 f8, bishop d7 h8, knight d5 c6, pawn a5 g6 b7 c7 e7 f7 h7.
15 white and 15 black pieces are on the board; the puzzle position arises after move 8.
The position in numbers
Black are ahead by 2 points of material (36 against 38; pawn = 1, knight and bishop = 3, rook = 5, queen = 9) — the tactic has to convert or outweigh that.
The white king stands on e1, the black king on e8.
It is White to move on move 8, with 36 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.
Black hold the bishop pair, an edge in open lines. The White king has 1 empty squares to step to right now — the fewer they are, the closer a mating net.
Solution & explanation
Main line
8. cxd5 Nb4 9. Bxb4 axb4 10. Nc2 Qg7 11. Nxb4
Why it works
- Great move! pawn to d5 keeps the pressure (+3.0).
- A brilliant blow: bishop to b4, and you stand better (+2.6).
- A natural move: knight to c2.
- Best move. knight to b4 is exactly what the engine plays (+2.5).
- You win a piece — the knight.
- If instead Nb4, then Bxb4 and you win the knight.
Move by move
- 8. cxd5 — pawn to d5 (capture)
- Nb4 — knight to b4
- 9. Bxb4 — bishop to b4 (capture)
- axb4 — pawn to b4 (capture)
- 10. Nc2 — knight to c2
- Qg7 — queen to g7
- 11. Nxb4 — knight to b4 (capture)
Types in this puzzle
Decoy
A sacrifice lures the king or a piece onto a fatal square.
A decoy is the mirror image of deflection: you sacrifice to drag the king or a piece onto a fatal square. The classic is a queen or rook sac whose capture pulls the king into a knight fork, a discovered check or mate. Find the square where the target will be hit, then find the offer it cannot refuse. Calculate to the very end — a decoy only works when the follow-up is forced.
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 #183.
SP-183 · ThroneScout — Centre-file king, rim knight: 204 of the 960 positions share this pattern.
The king starts on e1, the rooks on b1 and f1, the queen on g1.
The kingside rook already stands on f1, so castling short moves only the king, from e1 to g1.
A bishop starts in the corner on h1: it has a single diagonal, which the g-pawn unlocks, running out to a8.
One second-rank pawn starts with no defender at all: a2.
The setup belongs to the ThroneScout family; read right to left it becomes position 770.
The engine's main line opens with f4.
Morozov Balance Index: 80 of 100 — class A — most balanced. Engine evaluation of the starting position: +17 centipawns for White (depth 50, 400 000 000 nodes).
Explore position #183Provenance
Mined from the project's engine self-play games.
Pack 008 · SP-183
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