Attack on the uncastled king: bishop to b2 (a1·12)
c9-24238naming 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 1700 ShuffleRating — for advanced tacticians.
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 h3, rook c1 f1, bishop a1 b1, knight g1, pawn a2 c2 d2 e4 f4 h4 g5.
Black: king d8, queen h8, rook b4 f8, bishop b2 a8, knight c7 g8, pawn h5 e6 f6 a7 b7 d7 g7.
14 white and 15 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 (35 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 d1, the black king on d8.
It is White to move on move 12, with 31 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 7 pawns, Black 7. No file is fully open, so the heavy pieces have to be pried in. Half-open for White: b.
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. Bxb2 Rxb2 13. Qa3 Ne7 14. Qxb2 fxg5 15. hxg5
Why it works
- Brilliant! The bishop on b2 is a sacrifice that works — you stand better (+2.4).
- Well found: queen to a3 (+2.4).
- Precise: queen to b2 is the top choice (+2.5).
- Best move. pawn to g5 is exactly what the engine plays (+2.3).
- You win a piece — the rook.
- If instead Rxb2, then Qa3 and you stay on top.
Move by move
- 12. Bxb2 — bishop to b2 (capture)
- Rxb2 — rook to b2 (capture)
- 13. Qa3 — queen to a3
- Ne7 — knight to e7
- 14. Qxb2 — queen to b2 (capture)
- fxg5 — pawn to g5 (capture)
- 15. hxg5 — pawn to g5 (capture)
Types in this puzzle
Queen fork
The queen lands on a square from which it attacks two targets at once.
The queen strikes along files, ranks and diagonals, so she forks more often than any other piece. Look for a square where the queen attacks two undefended targets at once — most often a check combined with a loose piece. Diagonal blows are especially venomous: a slanting check that also eyes a rook in the corner is the classic of the genre. Remember that both targets must be unprotected, or your «fork» is just a shot into the air.
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 #848.
SP-848 · ThroneGuard — The king starts in the middle of the back rank, on d or e, and neither knight begins in a corner.
The king starts on d1, the rooks on c1 and f1, the queen on h1.
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 a1: it has a single diagonal, which the b-pawn unlocks, running out to h8.
The pawn on d2 is defended by the king alone — the same soft spot f2 is in the classical setup.
The setup belongs to the ThroneGuard family; read right to left it becomes position 111.
The engine's main line opens with g4.
Morozov Balance Index: 10 of 100 — class D — largest edge. Engine evaluation of the starting position: +43 centipawns for White (depth 46, 400 000 000 nodes).
Explore position #848Provenance
Mined from the project's engine self-play games.
Pack 013 · SP-848
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