Mate in 2: queen to b8 (a7·2)
c9-19993naming 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 1090 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 b2, queen a7, bishop c3 f3, knight a1 b6, pawn f2 e3 d4 c6.
Black: king d8, queen f8, bishop d7 e7, knight f6 c7, pawn h2 g4 f5 d6 e6.
10 white and 11 black pieces are on the board; the puzzle position arises after move 27.
The position in numbers
Black are ahead by 1 points of material (25 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 b2, the black king on d8.
It is White to move on move 27, with 37 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): a, b — natural highways for the rooks and queen. Half-open for White: g, h.
The White king has 6 empty squares to step to right now — the fewer they are, the closer a mating net.
Solution & explanation
Main line
27. Qb8+ Bc8 28. Qxc8#
Why it works
- Great move! queen to b8 keeps the pressure (#1).
- Spot on — queen to c8 (#).
- The line ends in a forced mate in 2.
- If instead Bc8, then Qxc8# and it is mate.
Move by move
- 27. Qb8+ — queen to b8 with check
- Bc8 — bishop to c8
- 28. Qxc8# — queen to c8 (capture) 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.
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 2
A forced checkmate in two moves.
Mate in two: your move, any reply, then the mating blow. Start with the most forcing first moves — checks and sacrifices that shrink the opponent's options to almost nothing. Against every single reply you must have a mate ready, so check them all without exception. The common failure is analyzing the pretty defense and forgetting the boring one.
About this position
These pieces come from starting position #249.
SP-249 · BastionScout — Off-centre king plus a rim knight (a/h): 168 positions carry this shape.
The king starts on c1, the rooks on b1 and h1, the queen on f1.
The king already stands on c1, so castling long moves only the rook, from b1 to d1.
The bishops stand on d1 and e1; their long diagonals reach h5 and a5 once the e- and d-pawns step aside.
One second-rank pawn starts with no defender at all: a2.
The setup belongs to the BastionScout family; read right to left it becomes position 617.
The engine's main line opens with e4, putting a pawn straight into the centre.
Morozov Balance Index: 6 of 100 — class D — largest edge. Engine evaluation of the starting position: +48 centipawns for White (depth 45, 400 000 000 nodes).
Explore position #249Provenance
Mined from the project's engine self-play games.
Pack 007 · SP-249
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