Winning blow: queen to a5 (b6·2)
c9-25144naming 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 1700 ShuffleRating — for advanced tacticians.
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 g1, queen b6, rook c1 f1, knight f5, pawn a2 h2 h3 e4.
Black: king a8, queen e8, rook e6 c8, bishop c6 f8, knight e5, pawn g5 f6.
9 white and 9 black pieces are on the board; the puzzle position arises after move 32.
The position in numbers
Black are ahead by 4 points of material (26 against 30; pawn = 1, knight and bishop = 3, rook = 5, queen = 9) — the tactic has to convert or outweigh that.
The white king stands on g1, the black king on a8.
It is White to move on move 32, with 45 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 4 pawns, Black 2. Files fully open (no pawns of either colour): b, c, d — natural highways for the rooks and queen. Half-open for White: f, g.
Black hold the bishop pair, an edge in open lines. 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
32. Qa5+ Kb7 33. Rb1+ Bb5 34. Rxb5+ Qxb5 35. Qxb5+
Why it works
- Great move! queen to a5 keeps the pressure (+3.2).
- Well found: rook to b1 (+3.0).
- Strong! rook to b5 is the sharp choice (+3.0).
- Great move! queen to b5 keeps the pressure (+3.2).
- You win a piece — the queen.
- If instead Kb7, then Rb1+ and you stay on top.
Move by move
- 32. Qa5+ — queen to a5 with check
- Kb7 — king to b7
- 33. Rb1+ — rook to b1 with check
- Bb5 — bishop to b5
- 34. Rxb5+ — rook to b5 (capture) with check
- Qxb5 — queen to b5 (capture)
- 35. Qxb5+ — queen to b5 (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.
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 #642.
SP-642 · ThroneScout — King on a central file (d/e) with a knight starting on the rim (a/h).
The king starts on d1, the rooks on b1 and e1, the queen on g1.
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.
A bishop starts in the corner on a1: it has a single diagonal, which the b-pawn unlocks, running out to h8.
The pawn on c2, d2 is defended by the king alone — the same soft spot f2 is in the classical setup.
The setup belongs to the ThroneScout family; read right to left it becomes position 215.
The engine's main line opens with f4.
Morozov Balance Index: 75 of 100 — class B — balanced. Engine evaluation of the starting position: +19 centipawns for White (depth 48, 400 000 000 nodes).
Explore position #642Provenance
Mined from the project's engine self-play games.
Pack 013 · SP-642
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