Winning blow: pawn to d3 (c2·19)
c9-24194naming 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 c1, queen e2, rook e1, bishop g2 d4, knight f3 b5, pawn b2 c2 h2 g3 a4.
Black: king b8, queen d8, rook a6, bishop g7 g8, knight d3 b4, pawn a5 d5 c6 g6 b7 h7.
12 white and 13 black pieces are on the board; the puzzle position arises after move 19.
The position in numbers
Black are ahead by 1 points of material (31 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 c1, the black king on b8.
It is White to move on move 19, with 5 legal replies to weigh — only the line that keeps the advantage solves the puzzle. White are in check right now, so every reply must answer the check.
White keeps 5 pawns, Black 6. Files fully open (no pawns of either colour): e, f — natural highways for the rooks and queen. Half-open for White: d.
The White king has 3 empty squares to step to right now — the fewer they are, the closer a mating net.
Solution & explanation
Main line
19. cxd3 cxb5 20. Qe8 Rd6 21. Bb6 Rc6+ 22. Qxc6
Why it works
- Great move! pawn to d3 keeps the pressure (+2.4).
- Spot on — queen to e8 (+2.5).
- Stunning! bishop to b6 gives up material but you stand better (+2.4).
- Brilliant! The queen on c6 is a sacrifice that works — you stand better (+2.4).
- You win a piece — the rook.
- If instead cxb5, then Qe8 and you stay on top.
Move by move
- 19. cxd3 — pawn to d3 (capture)
- cxb5 — pawn to b5 (capture)
- 20. Qe8 — queen to e8
- Rd6 — rook to d6
- 21. Bb6 — bishop to b6
- Rc6+ — rook to c6 with check
- 22. Qxc6 — queen to c6 (capture)
Types in this puzzle
Decoy
A sacrifice lures the king or a piece onto a fatal square.
A decoy is the mirror image of deflection: you sacrifice to drag the king or a piece onto a fatal square. The classic is a queen or rook sac whose capture pulls the king into a knight fork, a discovered check or mate. Find the square where the target will be hit, then find the offer it cannot refuse. Calculate to the very end — a decoy only works when the follow-up is forced.
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.
Overload
One defender guards two things — it cannot do both jobs.
Overloading exploits a defender with two jobs at once — guarding a piece and covering a mating square, for instance. It cannot do both: your first strike forces it to handle one duty and abandon the other. Find the overworked piece by asking what happens to each of its charges if it gets distracted. Then hit one target and collect the other — an overloaded defender only pretends to defend.
About this position
These pieces come from starting position #639.
SP-639 · BastionGuard — King shifted to c or f, knights kept clear of the edges — 168 positions in all.
The king starts on c1, the rooks on a1 and e1, the queen on d1.
The king already stands on c1, so castling long moves only the rook, from a1 to d1.
A bishop starts in the corner on h1: it has a single diagonal, which the g-pawn unlocks, running out to a8.
The pawn on b2 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 224.
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 48, 400 000 000 nodes).
Explore position #639Provenance
Mined from the project's engine self-play games.
Pack 008 · SP-639
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