Attack on the uncastled king: queen to d8 (d3·3)
c9-14852naming 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: a forcing sequence that ends the game — the king has no escape.
Mate in 4: a forced checkmate in four moves — every reply is covered.
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 2350 ShuffleRating — expert level — few solve it at first try.
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.
This is a forced mating attack. Start from the enemy king: which of its squares are already covered, and which move takes away the rest while keeping the king in check? Forcing moves — checks and captures — are what turn an attack into mate.
A mate in four is a longer forced net: each of your moves is a check or an irresistible threat, and the king is driven step by step to a square where it is finally trapped. Verify that the defender has exactly one reply at every branch.
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 g1, queen d3, rook d1 e1, bishop e5, pawn a2 b2 f2 h2 c3 g3 c7.
Black: king f8, rook g6 a8, knight e4, pawn f5 g5 c6 h6 a7.
12 white and 9 black pieces are on the board; the puzzle position arises after move 24.
The position in numbers
White are ahead by 11 points of material (29 against 18; 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 f8.
It is White to move on move 24, with 47 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 7 pawns, Black 5. Files fully open (no pawns of either colour): d, e — natural highways for the rooks and queen.
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
24. Qd8+ Rxd8 25. cxd8=Q+ Kf7 26. Rd7+ Ke6 27. Qe8#
Why it works
- Best move. queen to d8 is exactly what the engine plays (#3).
- Spot on — pawn to d8 (#2).
- Precise: rook to d7 is the top choice (#1).
- Best move. queen to e8 is exactly what the engine plays (#).
- The line ends in a forced mate in 4.
- If instead Rxd8, then cxd8=Q+ and you win the rook.
Move by move
- 24. Qd8+ — queen to d8 with check
- Rxd8 — rook to d8 (capture)
- 25. cxd8=Q+ — pawn to d8 (capture) with check
- Kf7 — king to f7
- 26. Rd7+ — rook to d7 with check
- Ke6 — king to e6
- 27. Qe8# — queen to e8 and it is checkmate
Types in this puzzle
Ladder mate
Two heavy pieces climb line by line, cutting off every retreat.
The ladder mate uses two heavy pieces climbing rung by rung: one cuts the king off along a line, the other checks on the next line, driving him toward the edge. It is the classic two-rook technique — check, the king retreats one rank, the other rook checks, until mate on the last rank. The only danger is the king creeping close enough to attack one of your rooks. If it does, simply slide that rook to the far side of the same line.
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.
Mate in 4+
A long forced mating combination.
Mate in four or longer is a marathon of forcing moves where the grip must never loosen. The tools are the same: checks, double threats and sacrifices that deny the opponent a single free tempo. Do not juggle the whole tree at once — walk the main line all the way to mate first, then verify the side branches. If somewhere the defender finds one quiet move that holds, your very first move was wrong.
About this position
These pieces come from starting position #423.
SP-423 · BastionGuard — King shifted to c or f, knights kept clear of the edges — 168 positions in all.
The king starts on f1, the rooks on a1 and g1, the queen on d1.
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 722.
The engine's main line opens with d4, putting a pawn straight into the centre.
Morozov Balance Index: 86 of 100 — class A — most balanced. Engine evaluation of the starting position: +15 centipawns for White (depth 46, 400 000 000 nodes).
Explore position #423Provenance
Mined from the project's engine self-play games.
Pack 015 · SP-423
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