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Winning blow: queen to b7 (b3·6)

Shuffle Rating 2010Theme: Chess960 twist: use the unusual starting setup of the pieces.
White to move — find the best continuation

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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 2010 ShuffleRating — expert level — few solve it at first try.

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 g1, queen b3, rook f4, knight e6, pawn a2 d2 g2 h3 d5.

Black: king h7, queen e5, rook a8 c8, knight h4, pawn d6.

9 white and 6 black pieces are on the board; the puzzle position arises after move 28.

The position in numbers

Black are ahead by 1 points of material (22 against 23; pawn = 1, knight and bishop = 3, rook = 5, queen = 9) — the tactic has to convert or outweigh that.

The white king stands on g1, the black king on h7.

It is White to move on move 28, with 48 legal replies to weigh — only the line that keeps the advantage solves the puzzle.

White keeps 5 pawns, Black 1. Files fully open (no pawns of either colour): b, c, e, f — natural highways for the rooks and queen.

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

28. Qb7+ Rc7 29. Qxc7+

Why it works

  • Great move! queen to b7 keeps the pressure (#4).
  • Well found: queen to c7 (#3).
  • You win a piece — the rook.
  • If instead Rc7, then Qxc7+ and you win the rook.

Move by move

  • 28. Qb7+ — queen to b7 with check
  • Rc7 — rook to c7
  • 29. Qxc7+ — queen to c7 (capture) with check

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.

Win the pinned piece

The pinned piece cannot run — attack it again and win it.

A pinned piece cannot flee, which means you can win it outright by attacking it one more time. Count attackers against defenders: if you outnumber them, the piece is yours. The best extra attacker is a pawn, since it costs less than anything it might capture. Do not rush the capture — build up the pressure first, then harvest.

Check chase

Every move is a check — the king is chased into losing ground.

In a check chase every one of your moves is a check, so the opponent never gets a free second. The king is herded across the board until it loses a piece or walks into a decisive blow. Such lines are the easiest to calculate: each check allows only a handful of replies, so try them all. Make it a habit to start calculating any sharp position with the checks — they are the most forcing moves on the board.

About this position

These pieces come from starting position #529.

SP-529 · ThroneGuard — A central king (d or e) and two knights tucked onto inner files: the family that holds the standard array, SP-518.

The king starts on e1, the rooks on b1 and h1, the queen on f1.

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.

A bishop starts in the corner on a1: it has a single diagonal, which the b-pawn unlocks, running out to h8.

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 ThroneGuard family; read right to left it becomes position 523.

The engine's main line opens with b4.

Morozov Balance Index: 51 of 100 — class B — balanced. Engine evaluation of the starting position: +26 centipawns for White (depth 46, 400 000 000 nodes).

Explore position #529

Provenance

Mined from the project's engine self-play games.

Pack 014 · SP-529

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