Winning blow: rook to b7 (b1·15)
c9-10099naming 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 2100 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.
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 d1, queen a2, rook b1 e1, bishop g1, knight f1, pawn d2 f2 h2 a3 e3 c6.
Black: king b8, rook d8, bishop a5, pawn b7 e7.
12 white and 5 black pieces are on the board; the puzzle position arises after move 25.
The position in numbers
White are ahead by 21 points of material (31 against 10; pawn = 1, knight and bishop = 3, rook = 5, queen = 9) — the tactic has to convert or outweigh that.
The white king stands on d1, the black king on b8.
It is White to move on move 25, with 32 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 6 pawns, Black 2. Files fully open (no pawns of either colour): g — natural highways for the rooks and queen. Half-open for White: b.
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. Rxb7+ Ka8 26. Qb3 Rd7 27. cxd7
Why it works
- Best move. rook to b7 is exactly what the engine plays (#4).
- queen to b3 develops smoothly.
- Precise: pawn to d7 is the top choice (#2).
- You win a piece — the rook.
- If instead Ka8, then Qb3 and you stay on top.
Move by move
- 25. Rxb7+ — rook to b7 (capture) with check
Types in this puzzle
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.
About this position
These pieces come from starting position #783.
SP-783 · 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 b1 and e1, the queen on a1.
The king already stands on c1, so castling long moves only the rook, from b1 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 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 176.
The engine's main line opens with b4.
Morozov Balance Index: 6 of 100 — class D — largest edge. Engine evaluation of the starting position: +48 centipawns for White (depth 44, 400 000 000 nodes).
Explore position #783Provenance
Mined from the project's engine self-play games.
Pack 015 · SP-783
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