Winning blow: queen to a4 (a6·2)
c9-15573naming 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 2290 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.
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 c2, queen a6, rook d7, bishop h4, pawn b2 h3 f4 g4 e5.
Black: king c6, queen b7, rook b3, bishop g7, pawn a4 c5 b6 g6 f7 h7.
9 white and 10 black pieces are on the board; the puzzle position arises after move 33.
The position in numbers
Black are ahead by 1 points of material (22 against 23; pawn = 1, knight and bishop = 3, rook = 5, queen = 9) — the tactic has to convert or outweigh that.
The white king stands on c2, the black king on c6.
It is White to move on move 33, with 36 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 5 pawns, Black 6. Files fully open (no pawns of either colour): d — natural highways for the rooks and queen. Half-open for White: a, c.
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
33. Qxa4+ b5 34. Qe4+ Kb6 35. Bd8+ Qc7 36. Bxc7+
Why it works
- Best move. queen to a4 is exactly what the engine plays (#5).
- Spot on — queen to e4 (#4).
- Precise: bishop to d8 is the top choice (#3).
- Best move. bishop to c7 is exactly what the engine plays (#2).
- You win a piece — the queen.
- If instead b5, then Qe4+ and you stay on top.
Move by move
- 33. Qxa4+ — queen to a4 (capture) with check
- b5 — pawn to b5
- 34. Qe4+ — queen to e4 with check
- Kb6 — king to b6
- 35. Bd8+ — bishop to d8 with check
- Qc7 — queen to c7
- 36. Bxc7+ — bishop to c7 (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.
Check chase
Every move is a check — the king is chased into losing ground.
In a check chase every one of your moves is a check, so the opponent never gets a free second. The king is herded across the board until it loses a piece or walks into a decisive blow. Such lines are the easiest to calculate: each check allows only a handful of replies, so try them all. Make it a habit to start calculating any sharp position with the checks — they are the most forcing moves on the board.
About this position
These pieces come from starting position #935.
SP-935 · RampartGuard — A wing king (b/g) with no knight on the a- or h-file.
The king starts on b1, the rooks on a1 and d1, the queen on f1.
From b1 the king makes the longest journey Chess960 allows when castling short: five squares to g1.
A bishop starts in the corner on h1: it has a single diagonal, which the g-pawn unlocks, running out to a8.
One second-rank pawn starts with no defender at all: h2.
The setup belongs to the RampartGuard family; read right to left it becomes position 18.
The engine's main line opens with e4, putting a pawn straight into the centre.
Morozov Balance Index: 0 of 100 — class D — largest edge. Engine evaluation of the starting position: +78 centipawns for White (depth 45, 400 000 000 nodes).
In 50 self-play games White scored 60.0% (95% CI 46.2–72.4%).
Explore position #935Provenance
Mined from the project's engine self-play games.
Pack 015 · SP-935
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