Attack on the uncastled king: queen to d8 (b6·2)
c9-24939naming 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.
Mate in 3: a forced sequence that ends in checkmate.
A fork made possible by the Chess960 piece placement.
Uncastled king: the enemy king is stuck in the centre — punish it before it castles.
Difficulty 1630 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.
In a mate in three every move must be forcing; the defender should never get a free tempo. Find the check or threat that herds the king, calculate the single defence to each, and confirm the net closes on the third move.
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.
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 b1, queen b6, rook c6, pawn c2 b4 e4 a5.
Black: king b8, queen d8, rook a8, bishop g8, knight e1, pawn a6 b7 f7 g7 h7.
7 white and 10 black pieces are on the board; the puzzle position arises after move 27.
The position in numbers
Black are ahead by 7 points of material (18 against 25; pawn = 1, knight and bishop = 3, rook = 5, queen = 9) — the tactic has to convert or outweigh that.
The white king stands on b1, the black king on b8.
It is White to move on move 27, with 29 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 4 pawns, Black 5. Files fully open (no pawns of either colour): d — natural highways for the rooks and queen. Half-open for White: f, g, h.
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. Qxd8+ Ka7 28. Rxa6+ bxa6 29. Qb6#
Why it works
- Great move! queen to d8 keeps the pressure (#2).
- Spot on — rook to a6 (#1).
- Precise: queen to b6 is the top choice (#).
- The line ends in a forced mate in 3.
- If instead Ka7, then Rxa6+ and you win the queen.
Move by move
- 27. Qxd8+ — queen to d8 (capture) with check
- Ka7 — king to a7
- 28. Rxa6+ — rook to a6 (capture) with check
- bxa6 — pawn to a6 (capture)
- 29. Qb6# — queen to b6 and it is checkmate
Types in this puzzle
Epaulette mate
The king's own pieces flank it like epaulettes — mate comes head-on.
In the epaulette mate the king stands between two of its own pieces — most often rooks — like an officer wearing epaulettes. The side squares are blocked by friends, there is no retreat, and the queen mates head-on from directly in front of the king. The sign: a king on the edge rank with both neighboring squares on that rank occupied by its own pieces. Remember, extra defenders crowding the king can be deadlier than no defenders at all.
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.
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.
About this position
These pieces come from starting position #925.
SP-925 · RampartScout — A wing-file king (b or g) and at least one corner knight: the rarest of the six families, just 72 positions.
The king starts on b1, the rooks on a1 and c1, the queen on e1.
From b1 the king makes the longest journey Chess960 allows when castling short: five squares to g1.
The bishops stand on d1 and g1; their long diagonals reach h5 and a7 once the e- and f-pawns step aside.
One second-rank pawn starts with no defender at all: g2.
The setup belongs to the RampartScout family; read right to left it becomes position 40.
The engine's main line opens with a4.
Morozov Balance Index: 43 of 100 — class C — noticeable edge. Engine evaluation of the starting position: +28 centipawns for White (depth 49, 400 000 000 nodes).
Explore position #925Provenance
Mined from the project's engine self-play games.
Pack 012 · SP-925
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