Winning blow: pawn to a8 (a7·8)
c9-16478naming 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 2060 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 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 c2, rook h1 b7, bishop e4 h8, pawn b2 f2 g2 c3 a7.
Black: king f7, bishop h5 e7, pawn g3 c4 h4 e6.
10 white and 7 black pieces are on the board; the puzzle position arises after move 39.
The position in numbers
White are ahead by 11 points of material (21 against 10; pawn = 1, knight and bishop = 3, rook = 5, queen = 9) — the tactic has to convert or outweigh that.
The white king stands on c2, the black king on f7.
It is White to move on move 39, with 41 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): d — natural highways for the rooks and queen. Half-open for White: e, h.
The White king has 3 empty squares to step to right now — the fewer they are, the closer a mating net.
Solution & explanation
Main line
39. a8=Q Bf3 40. Bxf3 e5 41. Bd5+
Why it works
- Sensible development: pawn to a8.
- Spot on — bishop to f3 (#3).
- Precise: bishop to d5 is the top choice (#3).
- You win a piece — the bishop.
- If instead Be2, then Qd8 and you win the pawn.
Move by move
- 39. a8=Q — pawn to a8
Types in this puzzle
Promotion
The pawn reaches the last rank and becomes a queen — decisively.
Promotion turns a pawn on the last rank into a queen and rewrites the evaluation on the spot. In tactics the passer rarely walks in for free — usually a sacrifice clears its path. Count the tempi: how many moves does the pawn need, and can the defender stop it in time? And watch the promotion square itself — it must be out of enemy reach or won by force in your combination.
About this position
These pieces come from starting position #557.
SP-557 · BastionGuard — Off-centre king (c/f), no knight on the a- or h-file.
The king starts on c1, the rooks on a1 and h1, the queen on f1.
The king already stands on c1, so castling long moves only the rook, from a1 to d1.
The bishops stand on d1 and g1; their long diagonals reach h5 and a7 once the e- and f-pawns step aside.
The pawn on b2 is defended by the king alone — the same soft spot f2 is in the classical setup.
The setup belongs to the BastionGuard family; read right to left it becomes position 504.
The engine's main line opens with e4, putting a pawn straight into the centre.
Morozov Balance Index: 0 of 100 — class D — largest edge. Engine evaluation of the starting position: +63 centipawns for White (depth 44, 400 000 000 nodes).
In 50 self-play games White scored 65.0% (95% CI 51.1–76.7%).
Explore position #557Provenance
Mined from the project's engine self-play games.
Pack 015 · SP-557
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