Attack on the uncastled king: bishop to a5 (d2·2)
c9-12913naming 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 1060 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, rook c1 h1, bishop d2 g2, knight f3 d5, pawn a2 e2 h2 b3 g3 c4 f4.
Black: king d8, queen b8, rook c8 h8, bishop e7 e8, knight a5 d6, pawn b5 c5 f6 a7 d7 g7 h7.
14 white and 15 black pieces are on the board; the puzzle position arises after move 18.
The position in numbers
Black are ahead by 9 points of material (29 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 18, with 41 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: d.
The White king has 4 empty squares to step to right now — the fewer they are, the closer a mating net.
Solution & explanation
Main line
18. Bxa5+ Rc7 19. Bxc7+ Qxc7 20. Nxc7
Why it works
- Best move. bishop to a5 is exactly what the engine plays (+2.8).
- Spot on — bishop to c7 (+2.8).
- Stunning! knight to c7 gives up material but you stand better (+2.7).
- You win a piece — the queen.
- If instead Rc7, then Bxc7+ and you win the rook.
Move by move
- 18. Bxa5+ — bishop to a5 (capture) with check
- Rc7 — rook to c7
- 19. Bxc7+ — bishop to c7 (capture) with check
- Qxc7 — queen to c7 (capture)
- 20. Nxc7 — knight to c7 (capture)
Types in this puzzle
Win the pinned piece
The pinned piece cannot run — attack it again and win it.
A pinned piece cannot flee, which means you can win it outright by attacking it one more time. Count attackers against defenders: if you outnumber them, the piece is yours. The best extra attacker is a pawn, since it costs less than anything it might capture. Do not rush the capture — build up the pressure first, then harvest.
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 #206.
SP-206 · 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 h1, the queen on a1.
Castling long simply swaps the two pieces: the king on d1 and the rook on c1 trade places.
The bishops stand on f1 and g1; their long diagonals reach a6 and a7 once the e- and f-pawns step aside.
Every pawn on the second rank is defended from the very first move.
The setup belongs to the ThroneGuard family; read right to left it becomes position 660.
The engine's main line opens with h3.
Morozov Balance Index: 75 of 100 — class A — most balanced. Engine evaluation of the starting position: +19 centipawns for White (depth 47, 400 000 000 nodes).
Explore position #206Provenance
Mined from the project's engine self-play games.
Pack 006 · SP-206
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