Attack on the uncastled king: knight to b4 (d3·12)
c9-25749naming 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 d1, queen e1, rook a1 g1, bishop f1 d2, knight c3 d3, pawn a2 b2 c2 g2 e3 h3 d4 f4.
Black: king d8, queen f8, rook a8 g8, bishop b4 d7, knight a5 g6, pawn d5 f5 e6 a7 b7 c7 g7 h7.
16 white and 16 black pieces are on the board; the puzzle position arises after move 10.
The position in numbers
Material is level — 39 points of pieces on each side (pawn = 1, knight and bishop = 3, rook = 5, queen = 9).
The white king stands on d1, the black king on d8.
It is White to move on move 10, with 30 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 8 pawns, Black 8. No file is fully open, so the heavy pieces have to be pried in.
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
10. Nxb4 Qxb4 11. Nb1 Qxb2 12. Bc3 Qxa1 13. Bxa1
Why it works
- Great move! knight to b4 keeps the pressure (+5.0).
- knight to b1 develops smoothly.
- Strong! bishop to c3 is the sharp choice (+4.8).
- Great move! bishop to a1 keeps the pressure (+4.8).
- You win a piece — the queen.
- If instead Qxb4, then Nb1 and you stay on top.
Move by move
- 10. Nxb4 — knight to b4 (capture)
- Qxb4 — queen to b4 (capture)
- 11. Nb1 — knight to b1
- Qxb2 — queen to b2 (capture)
- 12. Bc3 — bishop to c3
- Qxa1 — queen to a1 (capture)
- 13. Bxa1 — bishop to a1 (capture)
Types in this puzzle
Discovered attack
A piece steps aside and opens a second attack from the piece behind it.
A discovered attack works like a curtain: one piece steps off the line and unveils the long-range piece behind it. The beauty is that the moving piece can create a second threat of its own — two attacks in one move. Look for your stacked pairs: a bishop or rook behind a knight or pawn, aimed through them at something valuable. Send the front piece to the most aggressive square — a discovery without a second threat wastes half its power.
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 #630.
SP-630 · ThroneScout — King on a central file (d/e) with a knight starting on the rim (a/h).
The king starts on d1, the rooks on a1 and g1, the queen on e1.
Castling ends where it always does: king to g1 and rook to f1 on the short side, king to c1 and rook to d1 on the long one.
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 ThroneScout family; read right to left it becomes position 230.
The engine's main line opens with d4, putting a pawn straight into the centre.
Morozov Balance Index: 3 of 100 — class D — largest edge. Engine evaluation of the starting position: +51 centipawns for White (depth 47, 400 000 000 nodes).
Explore position #630Provenance
Mined from the project's engine self-play games.
Pack 008 · SP-630
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