Winning blow: pawn to a5 (a4·4)
c9-10241naming 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 b1, queen d6, rook a1 e1, bishop g1 g8, knight e2, pawn f2 g2 c3 a4 b4 e4 h4.
Black: king a7, queen c8, rook a8 e8, knight f8, pawn e5 h5 b6 f6 g6 b7 d7.
14 white and 12 black pieces are on the board; the puzzle position arises after move 17.
The position in numbers
White are ahead by 6 points of material (35 against 29; pawn = 1, knight and bishop = 3, rook = 5, queen = 9) — the tactic has to convert or outweigh that.
The white king stands on b1, the black king on a7.
It is White to move on move 17, with 45 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 7 pawns, Black 7. No file is fully open, so the heavy pieces have to be pried in. Half-open for White: d.
White hold the bishop pair, an edge in open lines. 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
17. a5 Qc6 18. axb6+ Kxb6 19. f3+
Why it works
- Great move! pawn to a5 keeps the pressure (#4).
- Well found: pawn to b6 (#3).
- Precise: pawn to f3 is the top choice (#2).
- You win decisive material (+15.0).
- If instead Qc6, then axb6+ and you stay on top.
Move by move
- 17. a5 — pawn to a5
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?
About this position
These pieces come from starting position #909.
SP-909 · RampartScout — Wing king plus a rim knight, and only 72 positions qualify — the rarest pattern of all.
The king starts on b1, the rooks on a1 and e1, the queen on c1.
From b1 the king makes the longest journey Chess960 allows when castling short: five squares to g1.
The bishops stand on d1 and g1; their long diagonals reach h5 and a7 once the e- and f-pawns step aside.
One second-rank pawn starts with no defender at all: g2.
The setup belongs to the RampartScout family; read right to left it becomes position 56.
The engine's main line opens with d4, putting a pawn straight into the centre.
Morozov Balance Index: 34 of 100 — class C — noticeable edge. Engine evaluation of the starting position: +31 centipawns for White (depth 45, 400 000 000 nodes).
Explore position #909Provenance
Mined from the project's engine self-play games.
Pack 015 · SP-909
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