Winning blow: queen to b8 (b4·5)
c9-25614naming 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 1430 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 b4, rook f1 b3, bishop e3, pawn b2 c2 d3 h3 g4 a5.
Black: king c8, queen d6, rook a6 g8, bishop g7, knight e6, pawn e5 g5 c7 h7.
11 white and 10 black pieces are on the board; the puzzle position arises after move 25.
The position in numbers
Black are ahead by 1 points of material (28 against 29; 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 c8.
It is White to move on move 25, with 46 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 6 pawns, Black 4. Files fully open (no pawns of either colour): f — natural highways for the rooks and queen. Half-open for White: e.
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. Qb8+ Kd7 26. Rf7+ Qe7 27. Qb5+ Kd8 28. Rxe7
Why it works
- Great move! queen to b8 keeps the pressure (+7.9).
- Well found: rook to f7 (+8.2).
- Precise: queen to b5 is the top choice (+8.2).
- Best move. rook to e7 is exactly what the engine plays (+7.8).
- You win a piece — the queen.
- If instead Kd7, then Rf7+ and you stay on top.
Move by move
- 25. Qb8+ — queen to b8 with check
- Kd7 — king to d7
- 26. Rf7+ — rook to f7 with check
- Qe7 — queen to e7
- 27. Qb5+ — queen to b5 with check
- Kd8 — king to d8
- 28. Rxe7 — rook to e7 (capture)
Types in this puzzle
Absolute pin
A piece is pinned against its king — it cannot legally move.
An absolute pin freezes a piece on the line between its own king and your long-range attacker: moving it is simply illegal. The pattern is three units on one straight line — your bishop, rook or queen, an enemy piece, and the enemy king behind it. A pinned piece neither attacks nor defends anything: treat it as if it were off the board. Pile up on it, ideally with a pawn, because running away is against the rules.
About this position
These pieces come from starting position #655.
SP-655 · BastionGuard — The king starts one file off-centre, on c or f, with neither knight in a corner.
The king starts on c1, the rooks on a1 and d1, the queen on e1.
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, c2 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 208.
The engine's main line opens with f4.
Morozov Balance Index: 51 of 100 — class B — balanced. Engine evaluation of the starting position: +26 centipawns for White (depth 45, 400 000 000 nodes).
Explore position #655Provenance
Mined from the project's engine self-play games.
Pack 011 · SP-655
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