Winning blow: pawn to a8 (a7·6)
c9-17837naming 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 1280 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 c1, rook g1, knight c3, pawn d2 f3 a4 e4 h4 a7 h7.
Black: king c8, knight c5, pawn c4 a5 e5 g5 c6 f6.
10 white and 8 black pieces are on the board; the puzzle position arises after move 27.
The position in numbers
White are ahead by 6 points of material (15 against 9; pawn = 1, knight and bishop = 3, rook = 5, queen = 9) — the tactic has to convert or outweigh that.
The white king stands on c1, the black king on c8.
It is White to move on move 27, with 31 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 7 pawns, Black 6. Files fully open (no pawns of either colour): b — natural highways for the rooks and queen. Half-open for White: c, g.
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
27. a8=Q+ Kc7 28. Qa7+ Nb7 29. h8=Q
Why it works
- Best move. pawn to a8 is exactly what the engine plays (#4).
- Spot on — queen to a7 (#4).
- A natural move: pawn to h8.
- You win decisive material (+15.0).
- If instead Kd7, then h8=Q and you win the pawn.
Move by move
- 27. a8=Q+ — pawn to a8 with check
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.
Passed pawn
Nothing can stop the passer — escort it to the last rank.
A passed pawn has no enemy pawns in front of it or on the neighboring files: only pieces can stop it. Check who can blockade the pawn or catch it with the king — if nobody can, the pawn is worth a whole piece. Push the passer with your pieces supporting it, and put your rook behind it. The beginner's mistake is shoving the pawn forward unprotected, straight into a capture.
About this position
These pieces come from starting position #702.
SP-702 · BastionGuard — King off-centre on c or f with both knights on inner files.
The king starts on c1, the rooks on a1 and h1, the queen on b1.
The king already stands on c1, so castling long moves only the rook, from a1 to d1.
The bishops stand on f1 and g1; their long diagonals reach a6 and a7 once the e- and f-pawns step aside.
The pawn on d2 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 452.
The engine's main line opens with e4, putting a pawn straight into the centre.
Morozov Balance Index: 40 of 100 — class C — noticeable edge. Engine evaluation of the starting position: +29 centipawns for White (depth 42, 400 000 000 nodes).
Explore position #702Provenance
Mined from the project's engine self-play games.
Pack 009 · SP-702
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