Winning blow: queen to b7 (a7·8)
c9-22529naming 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 1930 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 c1, queen a7, rook h1 b6, knight c3, pawn a2 c2 d2 f2 e3 h5.
Black: king c8, queen f6, rook c5 g8, knight c6 c7, pawn e4 a6 d7 h7.
11 white and 10 black pieces are on the board; the puzzle position arises after move 21.
The position in numbers
Black are ahead by 1 points of material (28 against 29; pawn = 1, knight and bishop = 3, rook = 5, queen = 9) — the tactic has to convert or outweigh that.
The white king stands on c1, the black king on c8.
It is White to move on move 21, with 38 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 6 pawns, Black 4. Files fully open (no pawns of either colour): b, g — natural highways for the rooks and queen.
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
21. Qb7+ Kd8 22. Rxc6 Rxc6 23. Qb8+ Ke7 24. Qxg8
Why it works
- Great move! queen to b7 keeps the pressure (+3.9).
- Well found: rook to c6 (+3.8).
- Strong! queen to b8 is the sharp choice (+4.3).
- Great move! queen to g8 keeps the pressure (+4.3).
- You win a piece — the rook.
- If instead Kd8, then Rxc6 and you win the knight.
Move by move
- 21. Qb7+ — queen to b7 with check
- Kd8 — king to d8
- 22. Rxc6 — rook to c6 (capture)
- Rxc6 — rook to c6 (capture)
- 23. Qb8+ — queen to b8 with check
- Ke7 — king to e7
- 24. Qxg8 — queen to g8 (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.
Sacrifice attack
Give up material to unleash a decisive attack.
A sacrificial attack gives up material on purpose to rip the king's shelter open and launch a decisive assault. The sac is sound when you get concrete assets in return: open lines to the king, tempi, pieces ready to pour in. The signs: a poorly sheltered king, your forces aimed at its home, defenders stranded far away. The iron rule is to calculate, not hope — once the material is gone, there is no way back.
Skewer
A line attack forces the valuable piece to move, exposing the one behind it.
A skewer is a pin turned inside out: the valuable piece stands in front and something cheaper hides behind it. The big piece must step aside, and you collect the one that was sheltering in its shadow. Scan for the enemy king or queen sharing a file, rank or diagonal with another enemy piece. The deadliest version comes with check — the king moves, the rook behind it dies.
About this position
These pieces come from starting position #259.
SP-259 · ThroneGuard — A central king (d or e) and two knights tucked onto inner files: the family that holds the standard array, SP-518.
The king starts on d1, the rooks on c1 and g1, the queen on f1.
Castling long simply swaps the two pieces: the king on d1 and the rook on c1 trade places.
A bishop starts in the corner on a1: it has a single diagonal, which the b-pawn unlocks, running out to h8.
The second rank carries 2 pawns with no defender at all: a2, h2.
The setup belongs to the ThroneGuard family; read right to left it becomes position 595.
The engine's main line opens with b3.
Morozov Balance Index: 98 of 100 — class A — most balanced. Engine evaluation of the starting position: +3 centipawns for White (depth 45, 400 000 000 nodes).
In 50 self-play games White scored 47.0% (95% CI 33.9–60.6%).
Explore position #259Provenance
Mined from the project's engine self-play games.
Pack 014 · SP-259
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