Winning blow: knight to d6 (b5·8)
c9-19527naming 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 1150 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 b2, queen g1, rook b1, bishop d3, knight b5, pawn c2 d2 h2 g3.
Black: king c8, queen c5, rook a6, bishop c6, knight e6, pawn c7 d7 g7 h7.
9 white and 9 black pieces are on the board; the puzzle position arises after move 21.
The position in numbers
Material is level — 24 points of pieces on each side (pawn = 1, knight and bishop = 3, rook = 5, queen = 9).
The white king stands on b2, the black king on c8.
It is White to move on move 21, with 35 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 4 pawns, Black 4. Files fully open (no pawns of either colour): a, b, e, f — natural highways for the rooks and queen.
The White king has 2 empty squares to step to right now — the fewer they are, the closer a mating net.
Solution & explanation
Main line
21. Nd6+ Qxd6 22. Bxa6+
Why it works
- Great move! knight to d6 keeps the pressure (+3.1).
- Well found: bishop to a6 (+3.2).
- You reach a winning position (+3.2).
- If instead Qxd6, then Bxa6+ and you stay on top.
Move by move
- 21. Nd6+ — knight to d6 with check
- Qxd6 — queen to d6 (capture)
- 22. Bxa6+ — bishop to a6 (capture) with check
Types in this puzzle
Discovered attack
A piece steps aside and opens a second attack from the piece behind it.
A discovered attack works like a curtain: one piece steps off the line and unveils the long-range piece behind it. The beauty is that the moving piece can create a second threat of its own — two attacks in one move. Look for your stacked pairs: a bishop or rook behind a knight or pawn, aimed through them at something valuable. Send the front piece to the most aggressive square — a discovery without a second threat wastes half its power.
Check chase
Every move is a check — the king is chased into losing ground.
In a check chase every one of your moves is a check, so the opponent never gets a free second. The king is herded across the board until it loses a piece or walks into a decisive blow. Such lines are the easiest to calculate: each check allows only a handful of replies, so try them all. Make it a habit to start calculating any sharp position with the checks — they are the most forcing moves on the board.
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 #850.
SP-850 · BastionGuard — Both knights begin inside the board while the king stands on c or f; a position and its mirror twin share this family.
The king starts on c1, the rooks on b1 and e1, the queen on h1.
The king already stands on c1, so castling long moves only the rook, from b1 to d1.
A bishop starts in the corner on a1: it has a single diagonal, which the b-pawn unlocks, running out to h8.
One second-rank pawn starts with no defender at all: a2.
The setup belongs to the BastionGuard family; read right to left it becomes position 103.
The engine's main line opens with e4, putting a pawn straight into the centre.
Morozov Balance Index: 31 of 100 — class C — noticeable edge. Engine evaluation of the starting position: +32 centipawns for White (depth 43, 400 000 000 nodes).
Explore position #850Provenance
Mined from the project's engine self-play games.
Pack 007 · SP-850
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