Attack on the uncastled king: bishop to b3 (c2·5)
c9-24084naming 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 1250 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 g1, rook d1 a3, bishop c2 c3, pawn b2 e2 f2 h2 g3 a4.
Black: king c8, queen e6, rook a8 e8, bishop d6 f7, pawn a5 c6 f6 g6 b7 d7 h7.
12 white and 13 black pieces are on the board; the puzzle position arises after move 21.
The position in numbers
Black are ahead by 1 points of material (31 against 32; 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 21, with 38 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 6 pawns, Black 7. No file is fully open, so the heavy pieces have to be pried in. Half-open for White: c, d.
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
21. Bb3 Qe7 22. Bxf7 Bxa3 23. Bxe8
Why it works
- Great move! bishop to b3 keeps the pressure (+2.4).
- A brilliant blow: bishop to f7, and you stand better (+2.9).
- Stunning! bishop to e8 gives up material but you stand better (+2.6).
- You win a piece — the rook.
- If instead Qe7, then Bxf7 and you win the bishop.
Move by move
- 21. Bb3 — bishop to b3
- Qe7 — queen to e7
- 22. Bxf7 — bishop to f7 (capture)
- Bxa3 — bishop to a3 (capture)
- 23. Bxe8 — bishop to e8 (capture)
Types in this puzzle
Skewer
A line attack forces the valuable piece to move, exposing the one behind it.
A skewer is a pin turned inside out: the valuable piece stands in front and something cheaper hides behind it. The big piece must step aside, and you collect the one that was sheltering in its shadow. Scan for the enemy king or queen sharing a file, rank or diagonal with another enemy piece. The deadliest version comes with check — the king moves, the rook behind it dies.
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 #936.
SP-936 · BastionScout — King off-centre on c or f with a knight starting on the rim (a/h).
The king starts on c1, the rooks on a1 and d1, the queen on g1.
The king already stands on c1, so castling long moves only the rook, from a1 to d1.
The bishops stand on b1 and e1; their long diagonals reach h7 and a5 once the c- and d-pawns step aside.
One second-rank pawn starts with no defender at all: e2.
The setup belongs to the BastionScout family; read right to left it becomes position 29.
The engine's main line opens with d4, putting a pawn straight into the centre.
Morozov Balance Index: 11 of 100 — class D — largest edge. Engine evaluation of the starting position: +42 centipawns for White (depth 44, 400 000 000 nodes).
Explore position #936Provenance
Mined from the project's engine self-play games.
Pack 009 · SP-936
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