Chess960 tactic on d6 (a6)
c9-12657naming 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.
Difficulty 2120 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.
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 e1, queen a6, rook f1 a7, knight b1, pawn a2 e2 g3 g4 f5.
Black: king d4, queen g8, rook d6 f8, knight d5, pawn h5 e6 f7 g7.
10 white and 9 black pieces are on the board; the puzzle position arises after move 31.
The position in numbers
White are ahead by 1 points of material (27 against 26; pawn = 1, knight and bishop = 3, rook = 5, queen = 9) — the tactic has to convert or outweigh that.
The white king stands on e1, the black king on d4.
It is White to move on move 31, with 37 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 5 pawns, Black 4. Files fully open (no pawns of either colour): b, c, d — natural highways for the rooks and queen. Half-open for White: 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
31. Qxd6 Kc4 32. Ra4+ Kb5 33. Qa6+ Kc5 34. Rc4#
Why it works
- Best move. queen to d6 is exactly what the engine plays (#3).
- Spot on — rook to a4 (#2).
- Precise: queen to a6 is the top choice (#1).
- Best move. rook to c4 is exactly what the engine plays (#).
- The line ends in a forced mate in 4.
- If instead Kc4, then Ra4+ and you win the rook.
Move by move
- 31. Qxd6 — queen to d6 (capture)
- Kc4 — king to c4
- 32. Ra4+ — rook to a4 with check
- Kb5 — king to b5
- 33. Qa6+ — queen to a6 with check
- Kc5 — king to c5
- 34. Rc4# — rook to c4 and it is checkmate
Types in this puzzle
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.
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.
Absolute pin
A piece is pinned against its king — it cannot legally move.
An absolute pin freezes a piece on the line between its own king and your long-range attacker: moving it is simply illegal. The pattern is three units on one straight line — your bishop, rook or queen, an enemy piece, and the enemy king behind it. A pinned piece neither attacks nor defends anything: treat it as if it were off the board. Pile up on it, ideally with a pawn, because running away is against the rules.
About this position
These pieces come from starting position #353.
SP-353 · ThroneScout — King in the middle of the rank, with a knight already committed to the corner.
The king starts on e1, the rooks on c1 and f1, the queen on g1.
The kingside rook already stands on f1, so castling short moves only the king, from e1 to g1.
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: a2.
The setup belongs to the ThroneScout family; read right to left it becomes position 315.
The engine's main line opens with f4.
Morozov Balance Index: 55 of 100 — class B — balanced. Engine evaluation of the starting position: +25 centipawns for White (depth 52, 400 000 000 nodes).
Explore position #353Provenance
Mined from the project's engine self-play games.
Pack 015 · SP-353
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