Winning blow: rook to b7 (b1·9)
c9-18055naming 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 1280 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 a5, rook b1 g1, bishop e1, pawn a2 f2 h2 e3 g4 c5.
Black: king c8, rook b7 e8, pawn d4 e5 g6 a7 f7 h7.
11 white and 9 black pieces are on the board; the puzzle position arises after move 22.
The position in numbers
White are ahead by 12 points of material (28 against 16; 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 c8.
It is White to move on move 22, with 38 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 6 pawns, Black 6. Files fully open (no pawns of either colour): b — 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
22. Rxb7 Kxb7 23. Qb5+ Ka8 24. Qxe8+
Why it works
- Best move. rook to b7 is exactly what the engine plays (#6).
- Well found: queen to b5 (#5).
- Precise: queen to e8 is the top choice (#3).
- You win a piece — the rook.
- If instead Kxb7, then Qb5+ and you stay on top.
Move by move
- 22. Rxb7 — rook to b7 (capture)
Types in this puzzle
Winning blow
Find the strike that wins material by force.
A winning blow is a forced material gain that does not fit a single textbook motif. The general tactical recipe applies: spot loose pieces, an awkwardly placed king, overloaded lines. Go through the forcing moves in order of violence — checks, captures, threats — because most combinations start with one of them. Do not judge by feel: calculate the concrete line until the outcome is beyond doubt.
About this position
These pieces come from starting position #699.
SP-699 · 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 g1, the queen on b1.
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.
One second-rank pawn starts with no defender at all: e2.
The setup belongs to the BastionGuard family; read right to left it becomes position 449.
The engine's main line opens with c3.
Morozov Balance Index: 4 of 100 — class D — largest edge. Engine evaluation of the starting position: +50 centipawns for White (depth 41, 400 000 000 nodes).
Explore position #699Provenance
Mined from the project's engine self-play games.
Pack 009 · SP-699
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