Castling-960 to the rescue on a1 (d1·17)
c9-21457naming tag (square·N)Opens in the app if installed, otherwise downloads the APK.
The tactical motive
Castling 960: the strongest move is to castle — drag the king onto its rook.
Chess960 twist: use the unusual starting setup of the pieces.
Winning tactic: there is a move that gains a decisive advantage — find it.
Difficulty 1760 ShuffleRating — for advanced tacticians.
White to move — find the best continuation
How to recognize this tactic
Chess960 castling still ends with king and rook on the classical squares (g1/f1 or c1/d1), but the path can be unusual. Watch which squares the king crosses and whether castling here opens a file, drops a defender or walks into a 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.
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 a7, rook a1 h1, bishop d3 h4, knight e4, pawn a2 b2 c2 g2 h2 f3.
Black: king c8, queen d5, rook d8 h8, bishop f8, knight b4 e7, pawn e5 a6 b6 c7 g7 h7.
13 white and 13 black pieces are on the board; the puzzle position arises after move 15.
The position in numbers
Material is level — 34 points of pieces on each side (pawn = 1, knight and bishop = 3, rook = 5, queen = 9).
The white king stands on d1, the black king on c8.
It is White to move on move 15, with 40 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 6 pawns, Black 6. Files fully open (no pawns of either colour): d — natural highways for the rooks and queen. Half-open for White: e.
White hold the bishop pair, an edge in open lines. The White king has 6 empty squares to step to right now — the fewer they are, the closer a mating net.
Solution & explanation
Main line
15. O-O-O Qb7 16. Qxb7+ Kxb7 17. Bxa6+ Nxa6 18. Rxd8
Why it works
- Great move! king to c1 keeps the pressure (+5.1).
- Well found: queen to b7 (+4.9).
- Strong! bishop to a6 is the sharp choice (+5.1).
- Great move! rook to d8 keeps the pressure (+5.1).
- You win a piece — the queen.
- If instead Qb7, then Qxb7+ and you win the queen.
Move by move
- 15. O-O-O — king to a1
- Qb7 — queen to b7
- 16. Qxb7+ — queen to b7 (capture) with check
- Kxb7 — king to b7 (capture)
- 17. Bxa6+ — bishop to a6 (capture) with check
- Nxa6 — knight to a6 (capture)
- 18. Rxd8 — rook to d8 (capture)
Types in this puzzle
960 castling C-side
Chess960 castling to the C-side — the king lands on c1 wherever it started.
C-side castling in Chess960 sends the king to c1 and the rook to d1, no matter where they began. Sometimes it is one small hop, sometimes a journey through the center — check in advance which squares must be empty and whether any of them are attacked. The rules match classical chess: neither piece has moved, and the king never passes through check. In the game, just drag the king onto the rook.
Discovered attack
A piece steps aside and opens a second attack from the piece behind it.
A discovered attack works like a curtain: one piece steps off the line and unveils the long-range piece behind it. The beauty is that the moving piece can create a second threat of its own — two attacks in one move. Look for your stacked pairs: a bishop or rook behind a knight or pawn, aimed through them at something valuable. Send the front piece to the most aggressive square — a discovery without a second threat wastes half its power.
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.
About this position
These pieces come from starting position #458.
SP-458 · 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 a1 and h1, the queen on g1.
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 e1 and f1; their long diagonals reach a5 and a6 once the d- and e-pawns step aside.
One second-rank pawn starts with no defender at all: b2.
The setup belongs to the ThroneGuard family; read right to left it becomes position 693.
The engine's main line opens with Nb3, bringing the knight out to b3.
Morozov Balance Index: 37 of 100 — class C — noticeable edge. Engine evaluation of the starting position: +30 centipawns for White (depth 48, 400 000 000 nodes).
Explore position #458Provenance
Mined from the project's engine self-play games.
Pack 013 · SP-458
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