Castling-960 to the rescue on a1 (d1·16)
c9-24402naming 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 1570 ShuffleRating — club-player level.
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 c4, rook a1, bishop a5, knight h1 e3, pawn a2 b2 e2 f2 g2.
Black: king d7, queen c6, rook b8 g8, bishop g1, knight f8 h8, pawn e7 f7 g7 h7.
11 white and 11 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 (28 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 d1, the black king on d7.
It is White to move on move 16, with 47 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 5 pawns, Black 4. Files fully open (no pawns of either colour): c, d — natural highways for the rooks and queen. Half-open for White: h.
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
16. O-O-O+ Qd6 17. Qc7+ Ke6 18. Rxd6+ exd6 19. Qxb8
Why it works
- Great move! king to c1 keeps the pressure (#6).
- Spot on — queen to c7 (+9.4).
- Precise: rook to d6 is the top choice (+9.0).
- Great move! queen to b8 keeps the pressure (+9.5).
- You win a piece — the queen.
- If instead Qd6, then Qc7+ and you stay on top.
Move by move
- 16. O-O-O+ — king to a1 with check
- Qd6 — queen to d6
- 17. Qc7+ — queen to c7 with check
- Ke6 — king to e6
- 18. Rxd6+ — rook to d6 (capture) with check
- exd6 — pawn to d6 (capture)
- 19. Qxb8 — queen to b8 (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.
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.
Royal fork
A fork with check: the king must move, and the second piece is lost.
A royal fork is a fork with check — one of the two targets is the king itself. The check must be answered first, so nobody is left to rescue the second piece. Look for squares where your piece gives check and simultaneously attacks an undefended queen or rook. It is the most reliable fork of all, because your opponent literally has no choice.
About this position
These pieces come from starting position #804.
SP-804 · ThroneScout — King on a central file (d/e) with a knight starting on the rim (a/h).
The king starts on d1, the rooks on a1 and g1, the queen on e1.
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 c1; their long diagonals reach h7 and h6 once the c- and d-pawns step aside.
Every pawn on the second rank is defended from the very first move.
The setup belongs to the ThroneScout family; read right to left it becomes position 158.
The engine's main line opens with e4, putting a pawn straight into the centre.
Morozov Balance Index: 37 of 100 — class C — noticeable edge. Engine evaluation of the starting position: +30 centipawns for White (depth 43, 400 000 000 nodes).
Explore position #804Provenance
Mined from the project's engine self-play games.
Pack 011 · SP-804
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