Attack on the uncastled king: queen to b7 (h1·15)
c9-26098naming 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.
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 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.
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 d1, queen h1, rook a1 e1, bishop d2, knight f1 f2, pawn a2 b2 c4 f4 g4 g5.
Black: king d8, queen g7, rook e2 a8, bishop b7 c7, knight f8 g8, pawn d4 b5 c5 a7 h7.
13 white and 13 black pieces are on the board; the puzzle position arises after move 18.
The position in numbers
Black are ahead by 2 points of material (34 against 36; pawn = 1, knight and bishop = 3, rook = 5, queen = 9) — the tactic has to convert or outweigh that.
The white king stands on d1, the black king on d8.
It is White to move on move 18, with 38 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 6 pawns, Black 5. Files fully open (no pawns of either colour): e — natural highways for the rooks and queen. Half-open for White: d, h.
Black hold the bishop pair, an edge in open lines. 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
18. Qxb7 Rxe1+ 19. Bxe1 Rb8 20. Qxa7 bxc4 21. Ba5
Why it works
- Great move! queen to b7 keeps the pressure (+2.7).
- Spot on — bishop to e1 (+2.7).
- Strong! queen to a7 is the sharp choice (+2.8).
- Best move. bishop to a5 is exactly what the engine plays (+2.7).
- You win a piece — the rook.
- If instead Rxe1+, then Bxe1 and you win the rook.
Move by move
- 18. Qxb7 — queen to b7 (capture)
- Rxe1+ — rook to e1 (capture) with check
- 19. Bxe1 — bishop to e1 (capture)
- Rb8 — rook to b8
- 20. Qxa7 — queen to a7 (capture)
- bxc4 — pawn to c4 (capture)
- 21. Ba5 — bishop to a5
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.
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 #948.
SP-948 · ThroneGuard — King on a central file (d/e) with both knights on inner files — the classic-type setup.
The king starts on d1, the rooks on a1 and e1, the queen on h1.
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.
The bishops stand on b1 and c1; their long diagonals reach h7 and h6 once the c- and d-pawns step aside.
One second-rank pawn starts with no defender at all: f2.
The setup belongs to the ThroneGuard family; read right to left it becomes position 14.
The engine's main line opens with Nf3, bringing the knight out to f3.
Morozov Balance Index: 65 of 100 — class B — balanced. Engine evaluation of the starting position: +22 centipawns for White (depth 45, 400 000 000 nodes).
Explore position #948Provenance
Mined from the project's engine self-play games.
Pack 008 · SP-948
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