Mate in 2: queen to b6 (a5·2)
c9-23472naming 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 2: the first move creates an unstoppable threat, the second delivers mate.
A fork made possible by the Chess960 piece placement.
Difficulty 1320 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.
Mate in two usually opens with a forcing move — a check, a capture or an unstoppable threat — that strips the king of squares or defenders, so the follow-up mate becomes unavoidable. Look for the first move that leaves the opponent only losing replies.
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 b1, queen a5, rook g1, bishop d4, pawn c2 h2 b3 g3 e4.
Black: king b7, queen c8, rook b8 e8, knight b6 g6, pawn f7 g7 h7.
9 white and 9 black pieces are on the board; the puzzle position arises after move 23.
The position in numbers
Black are ahead by 6 points of material (22 against 28; 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 23, with 47 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 5 pawns, Black 3. Files fully open (no pawns of either colour): a, d — natural highways for the rooks and queen. Half-open for White: f.
The White king has 5 empty squares to step to right now — the fewer they are, the closer a mating net.
Solution & explanation
Main line
23. Qxb6+ Ka8 24. Qa7#
Why it works
- Great move! queen to b6 keeps the pressure (#1).
- Spot on — queen to a7 (#).
- The line ends in a forced mate in 2.
- If instead Ka8, then Qa7# and it is mate.
Move by move
- 23. Qxb6+ — queen to b6 (capture) with check
- Ka8 — king to a8
- 24. Qa7# — queen to a7 and it is checkmate
Types in this puzzle
Supported queen mate
The queen delivers mate face to face, protected by a friend.
The supported queen mate is the most common pattern of all: the queen lands next to the king and mates because a friendly piece or pawn protects her. The king is helpless — capturing is impossible, and the queen covers every neighboring square herself. Hunt for a protected square beside the enemy king: a knight, bishop or pawn eyeing it turns her invasion into mate. Verify one thing — that the square really is defended, or the king eats her.
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 #826.
SP-826 · RampartScout — A knight in the corner and the king out on the wing (b/g); like every family, it is closed under mirror twins.
The king starts on b1, the rooks on a1 and g1, the queen on d1.
From b1 the king makes the longest journey Chess960 allows when castling short: five squares to g1.
The bishops stand on e1 and f1; their long diagonals reach a5 and a6 once the d- and e-pawns step aside.
One second-rank pawn starts with no defender at all: h2.
The setup belongs to the RampartScout family; read right to left it becomes position 133.
The engine's main line opens with a4.
Morozov Balance Index: 78 of 100 — class A — most balanced. Engine evaluation of the starting position: +18 centipawns for White (depth 48, 400 000 000 nodes).
Explore position #826Provenance
Mined from the project's engine self-play games.
Pack 010 · SP-826
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