Winning blow: rook to b4 (b3·2)
c9-24881naming 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 1290 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 a2, queen f2, rook b1 b3, bishop a6, knight e3 h7, pawn h2 a3 e4 g4 a5.
Black: king d8, queen d4, rook b8 f8, bishop a4, knight g6 e7, pawn b4 d6 e6 c7 f7.
12 white and 12 black pieces are on the board; the puzzle position arises after move 26.
The position in numbers
Material is level — 33 points of pieces on each side (pawn = 1, knight and bishop = 3, rook = 5, queen = 9).
The white king stands on a2, the black king on d8.
It is White to move on move 26, with 49 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 5 pawns, Black 5. No file is fully open, so the heavy pieces have to be pried in. Half-open for White: b, c, d, f.
The White king has 0 empty squares to step to right now — the fewer they are, the closer a mating net.
Solution & explanation
Main line
26. Rxb4 Rxb4 27. Rxb4 Qa7 28. Nxf8
Why it works
- Great move! rook to b4 keeps the pressure (+4.2).
- Well found: rook to b4 (+4.2).
- Precise: knight to f8 is the top choice (+4.0).
- You win a piece — the rook.
- If instead Rxb4, then Rxb4 and you stay on top.
Move by move
- 26. Rxb4 — rook to b4 (capture)
- Rxb4 — rook to b4 (capture)
- 27. Rxb4 — rook to b4 (capture)
- Qa7 — queen to a7
- 28. Nxf8 — knight to f8 (capture)
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.
Battery
Two pieces stacked on one line — the front one strikes with double force.
A battery stacks two long-range pieces on one line — a queen behind a bishop on a diagonal, or doubled rooks on a file. The front piece strikes with double force: capture it, and the piece behind recaptures with even more pressure. The battery is ready when both pieces already stare at one point and only the front strike is missing. Build batteries in advance on lines leading to the king — the doubling itself often breeds the combination.
Winning exchange
A forced series of captures on one square ends in your favour.
A winning exchange is a forced series of captures on one square that leaves you ahead in material. It is pure arithmetic: count the attackers and defenders of the square and note the value of every piece in the queue. Capture in the right order — cheap pieces first, expensive ones later — or a winning trade turns into a losing one. The classic error is stopping the count halfway and missing the opponent's final recapture.
About this position
These pieces come from starting position #834.
SP-834 · BastionScout — King off-centre on c or f with a knight starting on the rim (a/h).
The king starts on c1, the rooks on b1 and e1, the queen on g1.
The king already stands on c1, so castling long moves only the rook, from b1 to d1.
A bishop starts in the corner on a1: it has a single diagonal, which the b-pawn unlocks, running out to h8.
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 119.
The engine's main line opens with f4.
Morozov Balance Index: 89 of 100 — class A — most balanced. Engine evaluation of the starting position: +14 centipawns for White (depth 45, 400 000 000 nodes).
Explore position #834Provenance
Mined from the project's engine self-play games.
Pack 009 · SP-834
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