Winning blow: rook to b7 (b5)
c9-10413naming 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.
A fork made possible by the Chess960 piece placement.
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.
A set-up fork needs one preparing move before the fork lands — a check that drives the king onto the forking square, or a capture that lines the targets up. Find the preparation first, then the fork it makes possible.
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 h1, rook f4 b5, bishop a4, pawn a2 g2 h2 d3 e5 e6.
Black: king e8, rook e7 b8, bishop a7, knight e3, pawn a3 g6 b7 h7.
10 white and 9 black pieces are on the board; the puzzle position arises after move 31.
The position in numbers
Black are ahead by 1 points of material (19 against 20; pawn = 1, knight and bishop = 3, rook = 5, queen = 9) — the tactic has to convert or outweigh that.
The white king stands on h1, the black king on e8.
It is White to move on move 31, with 31 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): c, f — natural highways for the rooks and queen. Half-open for White: b.
The White king has 1 empty squares to step to right now — the fewer they are, the closer a mating net.
Solution & explanation
Main line
31. Rxb7+ Rd7 32. exd7+
Why it works
- Best move. rook to b7 is exactly what the engine plays (#4).
- Spot on — pawn to d7 (#3).
- You win a piece — the rook.
- If instead Rd7, then exd7+ and you win the rook.
Move by move
- 31. Rxb7+ — rook to b7 (capture) with check
- Rd7 — rook to d7
- 32. exd7+ — pawn to d7 (capture) with check
Types in this puzzle
Setup fork
The random setup allows a fork that classical chess never sees.
A setup fork is a double attack that exists only because of the unusual starting squares — in classical chess these targets never stand side by side. Look for pairs of undefended pieces on your opponent's back rank and for squares from which a knight or pawn hits both at once. Such forks usually appear within the first moves, before the pieces disperse. In every new position, note right away which starting pieces are defended by no one.
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.
Discovered check
The moving piece opens a check — and is free to grab anything meanwhile.
With a discovered check the moving piece unmasks a check from the piece standing behind it. While the king deals with the check, the piece that moved grabs whatever it likes, free of charge. Look for your long-range piece on a line with the enemy king, with exactly one of your own pieces in between. The rule: among all the ways to step aside, pick the one that captures or attacks the most expensive loot.
About this position
These pieces come from starting position #233.
SP-233 · BastionScout — King shifted to c or f, with a knight committed to the corner from move one.
The king starts on f1, the rooks on b1 and h1, the queen on c1.
Castling ends where it always does: king to g1 and rook to f1 on the short side, king to c1 and rook to d1 on the long one.
The bishops stand on d1 and e1; their long diagonals reach h5 and a5 once the e- and d-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 633.
The engine's main line opens with b4.
Morozov Balance Index: 96 of 100 — class A — most balanced. Engine evaluation of the starting position: +8 centipawns for White (depth 48, 400 000 000 nodes).
Explore position #233Provenance
Mined from the project's engine self-play games.
Pack 007 · SP-233
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