Winning blow: queen to b8 (b1)
c9-13448naming 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 1060 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 b1, rook c1 h1, bishop a1 d1, knight g3, pawn f2 h3 a4 e4 d5.
Black: king h8, queen b8, rook c8 f8, bishop a8 d8, knight e8 g8, pawn c5 e5 g5 g6 a7 h7.
12 white and 14 black pieces are on the board; the puzzle position arises after move 19.
The position in numbers
Black are ahead by 4 points of material (33 against 37; 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 h8.
It is White to move on move 19, with 37 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): b — natural highways for the rooks and queen. Half-open for White: c, g.
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
19. Qxb8 Rxb8 20. Bxe5+ Bf6 21. Bxb8
Why it works
- Great move! queen to b8 keeps the pressure (+3.6).
- Well found: bishop to e5 (+3.5).
- Strong! bishop to b8 is the sharp choice (+4.1).
- You win a piece — the queen.
- If instead Rxb8, then Bxe5+ and you stay on top.
Move by move
- 19. Qxb8 — queen to b8 (capture)
- Rxb8 — rook to b8 (capture)
- 20. Bxe5+ — bishop to e5 (capture) with check
- Bf6 — bishop to f6
- 21. Bxb8 — bishop to b8 (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.
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.
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.
About this position
These pieces come from starting position #481.
SP-481 · BastionGuard — The king starts one file off-centre, on c or f, with neither knight in a corner.
The king starts on f1, the rooks on c1 and h1, the queen on b1.
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.
One second-rank pawn starts with no defender at all: d2.
The setup belongs to the BastionGuard family; read right to left it becomes position 571.
The engine's main line opens with c4.
Morozov Balance Index: 99 of 100 — class A — most balanced. Engine evaluation of the starting position: +5 centipawns for White (depth 48, 400 000 000 nodes).
In 50 self-play games White scored 51.0% (95% CI 37.6–64.3%).
Explore position #481Provenance
Mined from the project's engine self-play games.
Pack 006 · SP-481
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