Winning blow: rook to b5 (b4·2)
c9-19238naming 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 1010 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 c2, rook h1 b4, bishop h3, knight d2 f3, pawn a2 h2 e4 f4 h4.
Black: king b6, rook b8 h8, bishop h6 g8, knight b5, pawn e5 g6 a7 b7 h7.
12 white and 11 black pieces are on the board; the puzzle position arises after move 18.
The position in numbers
White are ahead by 9 points of material (33 against 24; 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 b6.
It is White to move on move 18, with 48 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 5 pawns, Black 5. Files fully open (no pawns of either colour): c, d — natural highways for the rooks and queen. Half-open for White: b, g.
Black hold the bishop pair, an edge in open lines. 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
18. Rxb5+ Kxb5 19. Qb2+ Ka4 20. Bd7+
Why it works
- Great move! rook to b5 keeps the pressure (#18).
- Spot on — queen to b2 (#12).
- Precise: bishop to d7 is the top choice (#7).
- You win decisive material (+15.0).
- If instead Kxb5, then Qb2+ and you stay on top.
Move by move
- 18. Rxb5+ — rook to b5 (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 #254.
SP-254 · BastionScout — The king starts one file off-centre, on c or f, and a knight begins in a corner.
The king starts on c1, the rooks on b1 and h1, the queen on d1.
The king already stands on c1, so castling long moves only the rook, from b1 to d1.
The bishops stand on f1 and g1; their long diagonals reach a6 and a7 once the e- and f-pawns step aside.
One second-rank pawn starts with no defender at all: a2.
The setup belongs to the BastionScout family; read right to left it becomes position 612.
The engine's main line opens with f4.
Morozov Balance Index: 5 of 100 — class D — largest edge. Engine evaluation of the starting position: +49 centipawns for White (depth 47, 400 000 000 nodes).
Explore position #254Provenance
Mined from the project's engine self-play games.
Pack 006 · SP-254
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