Winning blow: queen to a8 (a3·4)
c9-23359naming 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.
Winning tactic: there is a move that gains a decisive advantage — find it.
Difficulty 1200 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.
This position hides a concrete tactic that wins material or mates. Start with the most forcing candidate moves — checks, captures and threats — and calculate each to a clear end before choosing; the winning line is usually the one the opponent cannot meet.
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 a3, rook a1, knight c5, pawn c2 h2 b4 e4 e5.
Black: king c8, queen e7, rook b6 d7, bishop a8, pawn g4 h4 b5 g5 e6 c7.
9 white and 11 black pieces are on the board; the puzzle position arises after move 33.
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 b2, the black king on c8.
It is White to move on move 33, with 36 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 5 pawns, Black 6. Files fully open (no pawns of either colour): a, d, f — natural highways for the rooks and queen. Half-open for White: g.
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
33. Qxa8+ Rb8 34. Qa6+ Kd8 35. Qxb5 Ke8 36. Qxb8+
Why it works
- Great move! queen to a8 keeps the pressure (+3.9).
- Spot on — queen to a6 (+4.2).
- Precise: queen to b5 is the top choice (+4.6).
- Great move! queen to b8 keeps the pressure (+4.9).
- You win a piece — the rook.
- If instead Rb8, then Qa6+ and you win the bishop.
Move by move
- 33. Qxa8+ — queen to a8 (capture) with check
- Rb8 — rook to b8
- 34. Qa6+ — queen to a6 with check
- Kd8 — king to d8
- 35. Qxb5 — queen to b5 (capture)
- Ke8 — king to e8
- 36. Qxb8+ — queen to b8 (capture) with check
Types in this puzzle
Queen fork
The queen lands on a square from which it attacks two targets at once.
The queen strikes along files, ranks and diagonals, so she forks more often than any other piece. Look for a square where the queen attacks two undefended targets at once — most often a check combined with a loose piece. Diagonal blows are especially venomous: a slanting check that also eyes a rook in the corner is the classic of the genre. Remember that both targets must be unprotected, or your «fork» is just a shot into the air.
Overload
One defender guards two things — it cannot do both jobs.
Overloading exploits a defender with two jobs at once — guarding a piece and covering a mating square, for instance. It cannot do both: your first strike forces it to handle one duty and abandon the other. Find the overworked piece by asking what happens to each of its charges if it gets distracted. Then hit one target and collect the other — an overloaded defender only pretends to defend.
About this position
These pieces come from starting position #721.
SP-721 · BastionGuard — The king starts one file off-centre, on c or f, with neither knight in a corner.
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.
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 BastionGuard family; read right to left it becomes position 427.
The engine's main line opens with e4, putting a pawn straight into the centre.
Morozov Balance Index: 20 of 100 — class D — largest edge. Engine evaluation of the starting position: +37 centipawns for White (depth 45, 400 000 000 nodes).
Explore position #721Provenance
Mined from the project's engine self-play games.
Pack 008 · SP-721
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