Winning blow: pawn to a7 (a6·12)
c9-16571naming 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 e1 a3, pawn b2 d3 b4 g4 a6.
Black: king b5, pawn e4 d6 f6.
8 white and 4 black pieces are on the board; the puzzle position arises after move 42.
The position in numbers
White are ahead by 12 points of material (15 against 3; 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 b5.
It is White to move on move 42, with 27 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): c, h — natural highways for the rooks and queen. Half-open for White: e, f.
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
42. a7 Kb6 43. a8=Q exd3+ 44. Rxd3
Why it works
- Sensible development: pawn to a7.
- pawn to a8 develops smoothly.
- Precise: rook to d3 is the top choice (#3).
- You win a piece — the pawn.
- If instead e3, then a8=Q and you win the pawn.
Move by move
- 42. a7 — pawn to a7
Types in this puzzle
Quiet move
No check, no capture — yet this modest move decides the game.
A quiet move gives no check and takes nothing — yet it decides the game by creating an unstoppable threat or stealing the king's last square. This is the hardest class of moves: the eye hunts for loud blows while a modest shift does the winning. The clue: every forcing try runs into a defense, so seek the move that strengthens the threat or takes squares away. Train yourself to ask: what if I neither capture nor check, but quietly improve?
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.
Rook endgame
The most common endgame — activity decides everything.
The rook endgame is the most common of all: rooks and pawns on the board. Its first law is activity — a rook behind a passed pawn beats a rook passively babysitting one. The sign of a correct plan is that your rook is attacking something, not guarding something. The typical error is locking your rook into defense: it is often better to give up a pawn and keep your rook and king active.
About this position
These pieces come from starting position #860.
SP-860 · BastionGuard — A c- or f-file king and two knights on inner files (b–g).
The king starts on c1, the rooks on a1 and e1, the queen on h1.
The king already stands on c1, so castling long moves only the rook, from a1 to d1.
The bishops stand on b1 and g1; their long diagonals reach h7 and a7 once the c- and f-pawns step aside.
Every pawn on the second rank is defended from the very first move.
The setup belongs to the BastionGuard family; read right to left it becomes position 108.
The engine's main line opens with e4, putting a pawn straight into the centre.
Morozov Balance Index: 37 of 100 — class C — noticeable edge. Engine evaluation of the starting position: +30 centipawns for White (depth 46, 400 000 000 nodes).
Explore position #860Provenance
Mined from the project's engine self-play games.
Pack 015 · SP-860
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