Winning blow: queen to b4 (b3·3)
c9-28218naming 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 1750 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 b3, rook e1, bishop d5, knight a3, pawn f2 g3 d4 h4.
Black: king g7, queen d8, rook a5, bishop a4, pawn h5 g6 b7 f7.
9 white and 8 black pieces are on the board; the puzzle position arises after move 27.
The position in numbers
White are ahead by 3 points of material (24 against 21; 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 g7.
It is White to move on move 27, with 47 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 4 pawns, Black 4. Files fully open (no pawns of either colour): a, c, e — natural highways for the rooks and queen. Half-open for White: b.
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
27. Qb4 Qxd5 28. Re5 Qf3 29. Qxa5
Why it works
- Great move! queen to b4 keeps the pressure (+3.9).
- Well found: rook to e5 (+3.9).
- Precise: queen to a5 is the top choice (+3.8).
- You reach a winning position (+3.8).
- If instead Qxd5, then Re5 and you stay on top.
Move by move
- 27. Qb4 — queen to b4
- Qxd5 — queen to d5 (capture)
- 28. Re5 — rook to e5
- Qf3 — queen to f3
- 29. Qxa5 — queen to a5 (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 #407.
SP-407 · BastionGuard — Off-centre king (c/f), no knight on the a- or h-file.
The king starts on f1, the rooks on a1 and g1, the queen on b1.
Castling short simply swaps the two pieces: the king on f1 and the rook on g1 trade places.
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 BastionGuard family; read right to left it becomes position 738.
The engine's main line opens with d4, putting a pawn straight into the centre.
Morozov Balance Index: 83 of 100 — class A — most balanced. Engine evaluation of the starting position: +16 centipawns for White (depth 45, 400 000 000 nodes).
Explore position #407Provenance
Mined from the project's engine self-play games.
Pack 013 · SP-407
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