Winning blow: knight to a5 (b7·2)
c9-27312naming 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 1560 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, queen a6, rook a1 e1, bishop f1 d2, knight e4 b7, pawn c2 g2 h2 f3.
Black: king b8, queen f5, rook d8 e8, bishop a5, knight a8 h8, pawn d5 e5 b6 a7 d7 g7 h7.
12 white and 14 black pieces are on the board; the puzzle position arises after move 17.
The position in numbers
Material is level — 35 points of pieces on each side (pawn = 1, knight and bishop = 3, rook = 5, queen = 9).
The white king stands on c1, the black king on b8.
It is White to move on move 17, with 47 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 4 pawns, Black 7. No file is fully open, so the heavy pieces have to be pried in. Half-open for White: a, b, d, e.
White hold the bishop pair, an edge in open lines. 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
17. Nxa5 bxa5 18. Qxa5 Qe6 19. Qxa7+
Why it works
- Best move. knight to a5 is exactly what the engine plays (#4).
- Spot on — queen to a5 (#4).
- Precise: queen to a7 is the top choice (#3).
- You win decisive material (+15.0).
- If instead bxa5, then Qxa5 and you stay on top.
Move by move
- 17. Nxa5 — knight to a5 (capture)
- bxa5 — pawn to a5 (capture)
- 18. Qxa5 — queen to a5 (capture)
- Qe6 — queen to e6
- 19. Qxa7+ — queen to a7 (capture) with check
Types in this puzzle
Relative pin
A piece shields a more valuable one behind it — moving it loses material.
In a relative pin the piece shields not its king but something valuable behind it, usually the queen. Moving is legal but costly, because the piece behind falls. Look for three units on one line: your long-range piece, a cheaper enemy piece, and an expensive one hiding behind. Beware the classic trap — a relatively pinned piece can still move with check or a bigger threat, so verify before you cash in.
Winning exchange
A forced series of captures on one square ends in your favour.
A winning exchange is a forced series of captures on one square that leaves you ahead in material. It is pure arithmetic: count the attackers and defenders of the square and note the value of every piece in the queue. Capture in the right order — cheap pieces first, expensive ones later — or a winning trade turns into a losing one. The classic error is stopping the count halfway and missing the opponent's final recapture.
Clearance
Clear your own piece out of the way — with tempo — for the decisive blow.
Clearance is about your own piece standing in the way of the decisive blow — so you move it aside, or even throw it away. The key is to clear with tempo: jump off with a check, a capture or a threat, giving the opponent no time to regroup. The telltale sign: you see a crushing queen or rook move, but one of your own pieces blocks the line or occupies the square. Do not cling to it — a clearance sacrifice usually costs less than a missed attack.
About this position
These pieces come from starting position #358.
SP-358 · ThroneScout — A knight starts on the edge (a/h) and the king sits centrally on d or e; the mirror twin stays in this family too.
The king starts on d1, the rooks on b1 and e1, the queen on g1.
Castling ends where it always does: king to g1 and rook to f1 on the short side, king to c1 and rook to d1 on the long one.
The bishops stand on c1 and f1; their long diagonals reach h6 and a6 once the d- and e-pawns step aside.
One second-rank pawn starts with no defender at all: a2.
The setup belongs to the ThroneScout family; read right to left it becomes position 310.
The engine's main line opens with f3.
Morozov Balance Index: 7 of 100 — class D — largest edge. Engine evaluation of the starting position: +46 centipawns for White (depth 46, 400 000 000 nodes).
Explore position #358Provenance
Mined from the project's engine self-play games.
Pack 011 · SP-358
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