Attack on the uncastled king: queen to a1 (c1·2)
c9-15887naming 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 f2, queen c1, rook h3, bishop e3 f5, knight b4, pawn e2 g2 b3 c3 f3 d4 h5.
Black: king f8, queen c7, rook a1 h8, bishop c4 b8, knight d8, pawn b5 d5 e5 c6 g7 h7.
13 white and 13 black pieces are on the board; the puzzle position arises after move 16.
The position in numbers
Black are ahead by 4 points of material (30 against 34; pawn = 1, knight and bishop = 3, rook = 5, queen = 9) — the tactic has to convert or outweigh that.
The white king stands on f2, the black king on f8.
It is White to move on move 16, with 45 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 7 pawns, Black 6. Files fully open (no pawns of either colour): a — natural highways for the rooks and queen.
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
16. Qxa1 exd4 17. Bxd4 O-O 18. bxc4 Rxf5 19. cxd5
Why it works
- Great move! queen to a1 keeps the pressure (+3.1).
- Spot on — bishop to d4 (+3.0).
- Precise: pawn to c4 is the top choice (+3.0).
- Best move. pawn to d5 is exactly what the engine plays (+2.9).
- You win a piece — the rook.
- If instead exd4, then Bxd4 and you win the rook.
Move by move
- 16. Qxa1 — queen to a1 (capture)
- exd4 — pawn to d4 (capture)
- 17. Bxd4 — bishop to d4 (capture)
- O-O — king to h8
- 18. bxc4 — pawn to c4 (capture)
- Rxf5 — rook to f5 (capture)
- 19. cxd5 — pawn to d5 (capture)
Types in this puzzle
Remove the defender
Capture the guard first — then take what it protected.
Removing the defender is the straightforward plan: capture the guard first, then take what it guarded. Unlike deflection, the defender is not lured away — it is traded off or destroyed on the spot. Stare at the target you crave and ask who defends it, and whether that defender can be profitably eaten. Count the whole capture sequence, not just the first move — the trade must pay off at the end.
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 #412.
SP-412 · BastionGuard — Both knights begin inside the board while the king stands on c or f; a position and its mirror twin share this family.
The king starts on f1, the rooks on a1 and h1, the queen on c1.
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 b1 and g1; their long diagonals reach h7 and a7 once the c- and f-pawns step aside.
The pawn on e2 is defended by the king alone — the same soft spot f2 is in the classical setup.
The setup belongs to the BastionGuard family; read right to left it becomes position 748.
The engine's main line opens with d4, putting a pawn straight into the centre.
Morozov Balance Index: 65 of 100 — class B — balanced. Engine evaluation of the starting position: +22 centipawns for White (depth 46, 400 000 000 nodes).
Explore position #412Provenance
Mined from the project's engine self-play games.
Pack 008 · SP-412
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