Chess960 tactic on a6 (b8)
c9-15246naming 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.
Difficulty 2400 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.
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 d6, rook d1, bishop c2 g3, knight b8, pawn h2 b3 c3 a4 h4.
Black: king b7, rook e3, bishop f7, pawn a5 d5 e5 b6 d7.
11 white and 8 black pieces are on the board; the puzzle position arises after move 29.
The position in numbers
White are ahead by 15 points of material (28 against 13; 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 b7.
It is White to move on move 29, with 44 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 5 pawns, Black 5. Files fully open (no pawns of either colour): f, g — natural highways for the rooks and queen. Half-open for White: d, e.
White 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
29. Na6 d4 30. Qb8+ Kc6 31. Qc7+ Kd5 32. Qxd7#
Why it works
- Sensible development: knight to a6.
- Spot on — queen to b8 (#2).
- Precise: queen to c7 is the top choice (#1).
- Best move. queen to d7 is exactly what the engine plays (#).
- The line ends in a forced mate in 4.
- If instead d4, then Qb8+ and you stay on top.
Move by move
- 29. Na6 — knight to a6
- d4 — pawn to d4
- 30. Qb8+ — queen to b8 with check
- Kc6 — king to c6
- 31. Qc7+ — queen to c7 with check
- Kd5 — king to d5
- 32. Qxd7# — queen to d7 (capture) 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.
Royal fork
A fork with check: the king must move, and the second piece is lost.
A royal fork is a fork with check — one of the two targets is the king itself. The check must be answered first, so nobody is left to rescue the second piece. Look for squares where your piece gives check and simultaneously attacks an undefended queen or rook. It is the most reliable fork of all, because your opponent literally has no choice.
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 #568.
SP-568 · ThroneGuard — A centre-file king with no knight on the edge; a position and its mirror twin always share this family.
The king starts on d1, the rooks on a1 and g1, 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 e1; their long diagonals reach h7 and a5 once the c- and d-pawns step aside.
One second-rank pawn starts with no defender at all: b2.
The setup belongs to the ThroneGuard family; read right to left it becomes position 493.
The engine's main line opens with g3.
Morozov Balance Index: 11 of 100 — class D — largest edge. Engine evaluation of the starting position: +42 centipawns for White (depth 44, 400 000 000 nodes).
Explore position #568Provenance
Mined from the project's engine self-play games.
Pack 015 · SP-568
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