Winning blow: pawn to c4 (c3·2)
c9-13562naming 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.
A fork made possible by the Chess960 piece placement.
Winning tactic: there is a move that gains a decisive advantage — find it.
Difficulty 1110 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.
A set-up fork needs one preparing move before the fork lands — a check that drives the king onto the forking square, or a capture that lines the targets up. Find the preparation first, then the fork it makes possible.
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 d3, rook h1 a5, bishop d4, knight f3, pawn c2 e2 c3 g3 f4 h4.
Black: king g8, queen d5, rook b8 f8, bishop d6, knight b5, pawn f5 h5 g6 d7 e7.
12 white and 11 black pieces are on the board; the puzzle position arises after move 22.
The position in numbers
White are ahead by 1 points of material (31 against 30; 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 g8.
It is White to move on move 22, with 46 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 6 pawns, Black 5. Files fully open (no pawns of either colour): a, b — natural highways for the rooks and queen. Half-open for White: d.
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
22. c4 Bb4 23. cxd5
Why it works
- Great move! pawn to c4 keeps the pressure (+4.7).
- Spot on — pawn to d5 (+4.1).
- You win a piece — the queen.
- If instead Bb4, then cxd5 and you win the queen.
Move by move
- 22. c4 — pawn to c4
- Bb4 — bishop to b4
- 23. cxd5 — pawn to d5 (capture)
Types in this puzzle
Setup fork
The random setup allows a fork that classical chess never sees.
A setup fork is a double attack that exists only because of the unusual starting squares — in classical chess these targets never stand side by side. Look for pairs of undefended pieces on your opponent's back rank and for squares from which a knight or pawn hits both at once. Such forks usually appear within the first moves, before the pieces disperse. In every new position, note right away which starting pieces are defended by no one.
Quiet move
No check, no capture — yet this modest move decides the game.
A quiet move gives no check and takes nothing — yet it decides the game by creating an unstoppable threat or stealing the king's last square. This is the hardest class of moves: the eye hunts for loud blows while a modest shift does the winning. The clue: every forcing try runs into a defense, so seek the move that strengthens the threat or takes squares away. Train yourself to ask: what if I neither capture nor check, but quietly improve?
About this position
These pieces come from starting position #748.
SP-748 · 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 c1, the rooks on a1 and h1, the queen on f1.
The king already stands on c1, so castling long moves only the rook, from a1 to d1.
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 d2 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 412.
The engine's main line opens with e4, putting a pawn straight into the centre.
Morozov Balance Index: 14 of 100 — class D — largest edge. Engine evaluation of the starting position: +42 centipawns for White (depth 45, 400 000 000 nodes).
In 50 self-play games White scored 55.0% (95% CI 41.3–67.9%).
Explore position #748Provenance
Mined from the project's engine self-play games.
Pack 007 · SP-748
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