Winning blow: queen to c4 (c3)
c9-09289naming 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 g1, queen c3, rook c1 f2, bishop a1 a2, knight g3 h5, pawn g2 h2 a4 f4.
Black: king c8, queen d5, rook e8 g8, bishop b6 a8, knight h4, pawn c4 f5 d6 a7 g7 h7.
12 white and 13 black pieces are on the board; the puzzle position arises after move 21.
The position in numbers
White are ahead by 1 points of material (35 against 34; 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 c8.
It is White to move on move 21, with 36 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 4 pawns, Black 6. Files fully open (no pawns of either colour): b, e — natural highways for the rooks and queen. Half-open for White: c, d.
The White king has 2 empty squares to step to right now — the fewer they are, the closer a mating net.
Solution & explanation
Main line
21. Qxc4+ Qxc4 22. Bxc4
Why it works
- Great move! queen to c4 keeps the pressure (+3.5).
- Spot on — bishop to c4 (+3.7).
- You reach a winning position (+3.7).
- If instead Qxc4, then Bxc4 and you stay on top.
Move by move
- 21. Qxc4+ — queen to c4 (capture) with check
- Qxc4 — queen to c4 (capture)
- 22. Bxc4 — bishop to c4 (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.
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.
Mate defense
Mate is threatened — parry it and stay on top.
Mate defense: your opponent is one move from mating you — but it is your turn, and that changes everything. Find the defense that kills the mating threat while keeping your advantage: often a check or a counter-threat that leaves no time for the mate. First name the exact square where the mate would land — otherwise you are defending blind. The mistake is playing a "defensive" move that does not actually remove the threat.
About this position
These pieces come from starting position #784.
SP-784 · ThroneScout — A knight starts on the edge (a/h) and the king sits centrally on d or e; the mirror twin stays in this family too.
The king starts on e1, the rooks on c1 and g1, the queen on d1.
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.
Every pawn on the second rank is defended from the very first move.
The setup belongs to the ThroneScout family; read right to left it becomes position 175.
The engine's main line opens with c4.
Morozov Balance Index: 1 of 100 — class D — largest edge. Engine evaluation of the starting position: +58 centipawns for White (depth 47, 400 000 000 nodes).
In 50 self-play games White scored 58.0% (95% CI 44.2–70.6%).
Explore position #784Provenance
Mined from the project's engine self-play games.
Pack 007 · SP-784
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