Attack on the uncastled king: knight to b7 (a5·27)
c9-13206naming 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 1560 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 d3, rook e1, bishop h1 d2, knight b1 a5, pawn a2 c2 f2 h2 g4 d5.
Black: king d8, queen f8, rook c8 g8, bishop e8, knight b6 b8, pawn d4 c5 g5 h5 a7 b7 f7.
13 white and 14 black pieces are on the board; the puzzle position arises after move 12.
The position in numbers
Black are ahead by 3 points of material (32 against 35; 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 d8.
It is White to move on move 12, with 53 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 6 pawns, Black 7. Files fully open (no pawns of either colour): e — natural highways for the rooks and queen. Half-open for White: b.
White hold the bishop pair, an edge in open lines. 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
12. Nxb7+ Kc7 13. d6+ Qxd6 14. Nxd6
Why it works
- Great move! knight to b7 keeps the pressure (+6.6).
- Well found: pawn to d6 (+7.1).
- Strong! knight to d6 is the sharp choice (+7.5).
- You win a piece — the queen.
- If instead Kc7, then d6+ and you stay on top.
Move by move
- 12. Nxb7+ — knight to b7 (capture) with check
- Kc7 — king to c7
- 13. d6+ — pawn to d6 with check
- Qxd6 — queen to d6 (capture)
- 14. Nxd6 — knight to d6 (capture)
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.
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.
Development punish
Half the army still asleep — the attack breaks through.
Punishing lazy development: half of your opponent's army is asleep on its starting squares, which means you outnumber him where the fight is. Count not the pieces on the board but the pieces in play — if five or more of his pieces have never moved, look for a forcing attack. The sign is a development lead plus open lines toward his king. Strike immediately: give him two quiet moves and the advantage evaporates.
About this position
These pieces come from starting position #75.
SP-75 · ThroneScout — Centre-file king, rim knight: 204 of the 960 positions share this pattern.
The king starts on d1, the rooks on c1 and g1, the queen on f1.
Castling long simply swaps the two pieces: the king on d1 and the rook on c1 trade places.
A bishop starts in the corner on h1: it has a single diagonal, which the g-pawn unlocks, running out to a8.
The second rank carries 3 pawns with no defender at all: a2, b2, h2.
The setup belongs to the ThroneScout family; read right to left it becomes position 881.
The engine's main line opens with g4.
Morozov Balance Index: 18 of 100 — class D — largest edge. Engine evaluation of the starting position: +38 centipawns for White (depth 46, 400 000 000 nodes).
Explore position #75Provenance
Mined from the project's engine self-play games.
Pack 011 · SP-75
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