Attack on the uncastled king: bishop to d5 (c4·5)
c9-13968naming 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 d2, rook c1, bishop g1 c4, knight d4, pawn h2 a5.
Black: king b8, rook d5 a8, bishop g4 g7, pawn a6 g6 h6 b7.
7 white and 9 black pieces are on the board; the puzzle position arises after move 34.
The position in numbers
Black are ahead by 4 points of material (16 against 20; pawn = 1, knight and bishop = 3, rook = 5, queen = 9) — the tactic has to convert or outweigh that.
The white king stands on d2, the black king on b8.
It is White to move on move 34, with 24 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 2 pawns, Black 4. Files fully open (no pawns of either colour): c, d, e, f — natural highways for the rooks and queen. Half-open for White: b, g.
The White king has 5 empty squares to step to right now — the fewer they are, the closer a mating net.
Solution & explanation
Main line
34. Bxd5 Be5 35. Kd3 Bc7 36. Rb1 O-O-O 37. Bxb7+
Why it works
- Great move! bishop to d5 keeps the pressure (+4.6).
- Spot on — king to d3 (+4.5).
- A natural move: rook to b1.
- Best move. bishop to b7 is exactly what the engine plays (+4.7).
- You win a piece — the rook.
- If instead Be5, then Kd3 and you win the rook.
Move by move
- 34. Bxd5 — bishop to d5 (capture)
- Be5 — bishop to e5
- 35. Kd3 — king to d3
- Bc7 — bishop to c7
- 36. Rb1 — rook to b1
- O-O-O — king to a8
- 37. Bxb7+ — bishop to b7 (capture) with check
Types in this puzzle
Absolute pin
A piece is pinned against its king — it cannot legally move.
An absolute pin freezes a piece on the line between its own king and your long-range attacker: moving it is simply illegal. The pattern is three units on one straight line — your bishop, rook or queen, an enemy piece, and the enemy king behind it. A pinned piece neither attacks nor defends anything: treat it as if it were off the board. Pile up on it, ideally with a pawn, because running away is against the rules.
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.
Counter-strike
Don't defend — answer the threat with a bigger one.
The counter-strike: instead of defending against the threat, you answer with a bigger threat of your own. While your opponent grabs a pawn, you deliver mate — the arithmetic favors you. Look for a counter when direct defenses fail: do you have a check, an attack on the queen, a mating threat? The beginner's error is meeting every threat with a reflexive defense without checking the counterattacking resources first.
About this position
These pieces come from starting position #902.
SP-902 · RampartScout — The king starts on b or g while a knight begins on the a- or h-file — the smallest family.
The king starts on b1, the rooks on a1 and e1, the queen on d1.
From b1 the king makes the longest journey Chess960 allows when castling short: five squares to g1.
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 RampartScout family; read right to left it becomes position 54.
The engine's main line opens with e4, putting a pawn straight into the centre.
Morozov Balance Index: 2 of 100 — class D — largest edge. Engine evaluation of the starting position: +62 centipawns for White (depth 48, 400 000 000 nodes).
In 50 self-play games White scored 54.0% (95% CI 40.4–67.0%).
Explore position #902Provenance
Mined from the project's engine self-play games.
Pack 008 · SP-902
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