Winning blow: rook to a1 (d1·2)
c9-24534naming 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.
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.
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 d2, rook d1 h1, bishop g2, knight d5, pawn a2 c2 b3 e4 f4 h4 g5.
Black: king g8, queen g4, rook e8 f8, bishop a1, knight e6 d7, pawn c5 a6 d6 g6 e7 f7 h7.
13 white and 14 black pieces are on the board; the puzzle position arises after move 18.
The position in numbers
Black are ahead by 3 points of material (32 against 35; 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 g8.
It is White to move on move 18, with 42 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. Rxa1 Nd4 19. c3 e6 20. Nc7 f6 21. cxd4
Why it works
- Great move! rook to a1 keeps the pressure (+3.1).
- Well found: pawn to c3 (+3.0).
- A natural move: knight to c7.
- Best move. pawn to d4 is exactly what the engine plays (+3.9).
- You win a piece — the bishop.
- If instead Nd4, then c3 and you win the bishop.
Move by move
- 18. Rxa1 — rook to a1 (capture)
- Nd4 — knight to d4
- 19. c3 — pawn to c3
- e6 — pawn to e6
- 20. Nc7 — knight to c7
- f6 — pawn to f6
- 21. cxd4 — pawn to d4 (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.
About this position
These pieces come from starting position #19.
SP-19 · BastionGuard — The king starts one file off-centre, on c or f, with neither knight in a corner.
The king starts on f1, the rooks on e1 and g1, the queen on c1.
Castling short simply swaps the two pieces: the king on f1 and the rook on g1 trade places.
A bishop starts in the corner on a1: it has a single diagonal, which the b-pawn unlocks, running out to h8.
The second rank carries 2 pawns with no defender at all: a2, h2.
The setup belongs to the BastionGuard family; read right to left it becomes position 931.
The engine's main line opens with g3.
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 #19Provenance
Mined from the project's engine self-play games.
Pack 008 · SP-19
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