Attack on the uncastled king: queen to b7 (b2·2)
c9-10809naming 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 piece strikes across the board from its Chess960 starting square.
A fork made possible by the Chess960 piece placement.
Uncastled king: the enemy king is stuck in the centre — punish it before it castles.
Winning tactic: there is a move that gains a decisive advantage — find it.
Difficulty 920 ShuffleRating — for beginners taking their first steps in Chess960 tactics.
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.
From some Chess960 setups a bishop or queen rakes a long diagonal straight from move one. Trace those long-range lines into the enemy camp: a single opened file or diagonal can create an immediate pin, skewer or mating threat.
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.
An uncastled king in the centre is a standing target. Look for ways to open the central files and diagonals against it with checks and threats before it can shelter — every tempo the king spends in the middle is a chance for a combination.
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 f1, queen b2, rook b1 g3, bishop c1, knight d1 e1, pawn a2 e2 f2 h2 c3 d4.
Black: king f8, queen b7, rook b8 g8, bishop g4 h8, knight a6 e8, pawn g5 d6 a7 e7 f7 h7.
13 white and 14 black pieces are on the board; the puzzle position arises after move 10.
The position in numbers
Black are ahead by 3 points of material (34 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 f1, the black king on f8.
It is White to move on move 10, with 37 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 6 pawns, Black 6. Files fully open (no pawns of either colour): b — natural highways for the rooks and queen. Half-open for White: g.
Black hold the bishop pair, an edge in open lines. The White king has 1 empty squares to step to right now — the fewer they are, the closer a mating net.
Solution & explanation
Main line
10. Qxb7 Rxb7 11. Rxb7
Why it works
- Great move! queen to b7 keeps the pressure (+4.1).
- Well found: rook to b7 (+4.1).
- You win a piece — the queen.
- If instead Rxb7, then Rxb7 and you win the queen.
Move by move
- 10. Qxb7 — queen to b7 (capture)
- Rxb7 — rook to b7 (capture)
- 11. Rxb7 — rook to b7 (capture)
Types in this puzzle
Long-range opener
From its unusual home square a long-range piece strikes across the board.
The long-range opener: a bishop, rook or queen strikes across the whole board straight from its starting area. In Chess960 the long-range pieces sit on unfamiliar squares, and a single pawn move can uncover a shot deep into the enemy camp. In the opening, trace with your eyes the diagonals and files of every long-range piece — yours and theirs. The mistake is pushing a pawn without checking whose line you have just opened.
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.
Clearance
Clear your own piece out of the way — with tempo — for the decisive blow.
Clearance is about your own piece standing in the way of the decisive blow — so you move it aside, or even throw it away. The key is to clear with tempo: jump off with a check, a capture or a threat, giving the opponent no time to regroup. The telltale sign: you see a crushing queen or rook move, but one of your own pieces blocks the line or occupies the square. Do not cling to it — a clearance sacrifice usually costs less than a missed attack.
About this position
These pieces come from starting position #391.
SP-391 · 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 b1 and g1, the queen on a1.
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 754.
The engine's main line opens with b3.
Morozov Balance Index: 69 of 100 — class B — balanced. Engine evaluation of the starting position: +21 centipawns for White (depth 41, 400 000 000 nodes).
Explore position #391Provenance
Mined from the project's engine self-play games.
Pack 004 · SP-391
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