Winning blow: queen to a6 (b6)
c9-11305naming 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 1200 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 b1, queen b6, rook d1 h1, knight c5 d5, pawn a2 g2 h2 b3.
Black: king c8, queen g7, rook e8 h8, bishop e5 a8, knight a6 d8, pawn f5 d7.
10 white and 10 black pieces are on the board; the puzzle position arises after move 27.
The position in numbers
Black are ahead by 4 points of material (29 against 33; pawn = 1, knight and bishop = 3, rook = 5, queen = 9) — the tactic has to convert or outweigh that.
The white king stands on b1, the black king on c8.
It is White to move on move 27, with 48 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): c, e — natural highways for the rooks and queen. Half-open for White: d, f.
Black hold the bishop pair, an edge in open lines. 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
27. Qxa6+ Kb8 28. Nb6 Bb7 29. Nxb7 Qxg2 30. Nxd7+
Why it works
- Great move! queen to a6 keeps the pressure (+5.4).
- Well found: knight to b6 (+5.6).
- Precise: knight to b7 is the top choice (+5.7).
- Best move. knight to d7 is exactly what the engine plays (+4.4).
- You win a piece — the bishop.
- If instead Kb8, then Nb6 and you win the knight.
Move by move
- 27. Qxa6+ — queen to a6 (capture) with check
- Kb8 — king to b8
- 28. Nb6 — knight to b6
- Bb7 — bishop to b7
- 29. Nxb7 — knight to b7 (capture)
- Qxg2 — queen to g2 (capture)
- 30. Nxd7+ — knight 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.
Only move
Everything else loses — find the only move that holds.
An only move is a position where everything loses except one single continuation. You cannot play "by hand" here: run through fundamentally different defenses — run away, block, trade, counterattack — and discard the ones that fail. The hallmark of these puzzles is that the obvious moves lose quickly while the solution often looks strange. First understand exactly what the threat is — then the one saving move reveals itself.
Overload
One defender guards two things — it cannot do both jobs.
Overloading exploits a defender with two jobs at once — guarding a piece and covering a mating square, for instance. It cannot do both: your first strike forces it to handle one duty and abandon the other. Find the overworked piece by asking what happens to each of its charges if it gets distracted. Then hit one target and collect the other — an overloaded defender only pretends to defend.
About this position
These pieces come from starting position #528.
SP-528 · ThroneGuard — King on a central file (d/e) with both knights on inner files — the classic-type setup.
The king starts on e1, the rooks on c1 and h1, the queen on f1.
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 d2 is defended by the king alone — the same soft spot f2 is in the classical setup.
The setup belongs to the ThroneGuard family; read right to left it becomes position 527.
The engine's main line opens with c4.
Morozov Balance Index: 59 of 100 — class B — balanced. Engine evaluation of the starting position: +24 centipawns for White (depth 49, 400 000 000 nodes).
Explore position #528Provenance
Mined from the project's engine self-play games.
Pack 007 · SP-528
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