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Winning blow: knight to b5 (d4·2)

Shuffle Rating 1150Theme: 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.

Winning tactic: there is a move that gains a decisive advantage — find it.

Difficulty 1150 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 b1, queen g1, rook d1 e1, bishop a1, knight d4, pawn c2 h2 b3 a4 f4 e7.

Black: king c7, queen f6, rook d5 e8, bishop b4 c8, knight f5, pawn a5 b6 c6 g6 h7.

12 white and 12 black pieces are on the board; the puzzle position arises after move 25.

The position in numbers

Black are ahead by 2 points of material (31 against 33; pawn = 1, knight and bishop = 3, rook = 5, queen = 9) — the tactic has to convert or outweigh that.

The white king stands on b1, the black king on c7.

It is White to move on move 25, with 33 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): d — natural highways for the rooks and queen. Half-open for White: g.

Black hold the bishop pair, an edge in open lines. 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

25. Nb5+ Rxb5 26. Bxf6

Why it works

  • Great move! knight to b5 keeps the pressure (+4.4).
  • Well found: bishop to f6 (+4.3).
  • You win a piece — the queen.
  • If instead Rxb5, then Bxf6 and you win the queen.

Move by move

  • 25. Nb5+ — knight to b5 with check
  • Rxb5 — rook to b5 (capture)
  • 26. Bxf6 — bishop to f6 (capture)

Types in this puzzle

Discovered attack

A piece steps aside and opens a second attack from the piece behind it.

A discovered attack works like a curtain: one piece steps off the line and unveils the long-range piece behind it. The beauty is that the moving piece can create a second threat of its own — two attacks in one move. Look for your stacked pairs: a bishop or rook behind a knight or pawn, aimed through them at something valuable. Send the front piece to the most aggressive square — a discovery without a second threat wastes half its power.

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.

Clearance

Clear your own piece out of the way — with tempo — for the decisive blow.

Clearance is about your own piece standing in the way of the decisive blow — so you move it aside, or even throw it away. The key is to clear with tempo: jump off with a check, a capture or a threat, giving the opponent no time to regroup. The telltale sign: you see a crushing queen or rook move, but one of your own pieces blocks the line or occupies the square. Do not cling to it — a clearance sacrifice usually costs less than a missed attack.

About this position

These pieces come from starting position #850.

SP-850 · 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 b1 and e1, the queen on h1.

The king already stands on c1, so castling long moves only the rook, from b1 to d1.

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

One second-rank pawn starts with no defender at all: a2.

The setup belongs to the BastionGuard family; read right to left it becomes position 103.

The engine's main line opens with e4, putting a pawn straight into the centre.

Morozov Balance Index: 31 of 100 — class C — noticeable edge. Engine evaluation of the starting position: +32 centipawns for White (depth 43, 400 000 000 nodes).

Explore position #850

Provenance

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

Pack 007 · SP-850

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