Winning blow: knight to d6 (b5·15)
c9-07389naming 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.
A fork made possible by the Chess960 piece placement.
Winning tactic: there is a move that gains a decisive advantage — find it.
Difficulty 1290 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.
A set-up fork needs one preparing move before the fork lands — a check that drives the king onto the forking square, or a capture that lines the targets up. Find the preparation first, then the fork it makes possible.
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 d1, queen b3, rook a1 f1, bishop g1, knight h1 b5, pawn b2 c2 d2 g2 h2 a4 e5.
Black: king b7, queen e8, rook d8 f8, bishop e7 g8, knight c4 h8, pawn f5 h5 a6 e6 c7 g7.
14 white and 14 black pieces are on the board; the puzzle position arises after move 13.
The position in numbers
Black are ahead by 2 points of material (35 against 37; pawn = 1, knight and bishop = 3, rook = 5, queen = 9) — the tactic has to convert or outweigh that.
The white king stands on d1, the black king on b7.
It is White to move on move 13, with 44 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 7 pawns, Black 6. No file is fully open, so the heavy pieces have to be pried in. Half-open for White: f.
Black 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
13. Nd6+ Kc6 14. Qxc4+ Kd7 15. Nxe8
Why it works
- Great move! knight to d6 keeps the pressure (+6.3).
- Spot on — queen to c4 (+6.6).
- Strong! knight to e8 is the sharp choice (+6.7).
- You win a piece — the queen.
- If instead Kc6, then Qxc4+ and you win the knight.
Move by move
- 13. Nd6+ — knight to d6 with check
- Kc6 — king to c6
- 14. Qxc4+ — queen to c4 (capture) with check
- Kd7 — king to d7
- 15. Nxe8 — knight to e8 (capture)
Types in this puzzle
Setup fork
The random setup allows a fork that classical chess never sees.
A setup fork is a double attack that exists only because of the unusual starting squares — in classical chess these targets never stand side by side. Look for pairs of undefended pieces on your opponent's back rank and for squares from which a knight or pawn hits both at once. Such forks usually appear within the first moves, before the pieces disperse. In every new position, note right away which starting pieces are defended by no one.
Royal fork
A fork with check: the king must move, and the second piece is lost.
A royal fork is a fork with check — one of the two targets is the king itself. The check must be answered first, so nobody is left to rescue the second piece. Look for squares where your piece gives check and simultaneously attacks an undefended queen or rook. It is the most reliable fork of all, because your opponent literally has no choice.
Development punish
Half the army still asleep — the attack breaks through.
Punishing lazy development: half of your opponent's army is asleep on its starting squares, which means you outnumber him where the fight is. Count not the pieces on the board but the pieces in play — if five or more of his pieces have never moved, look for a forcing attack. The sign is a development lead plus open lines toward his king. Strike immediately: give him two quiet moves and the advantage evaporates.
About this position
These pieces come from starting position #637.
SP-637 · BastionScout — A c- or f-file king with at least one knight out on the edge.
The king starts on c1, the rooks on a1 and f1, the queen on e1.
The king already stands on c1, so castling long moves only the rook, from a1 to d1.
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 BastionScout family; read right to left it becomes position 232.
The engine's main line opens with e4, putting a pawn straight into the centre.
Morozov Balance Index: 39 of 100 — class C — noticeable edge. Engine evaluation of the starting position: +21 centipawns for White (depth 44, 400 000 000 nodes).
In 50 self-play games White scored 57.0% (95% CI 43.3–69.7%).
Explore position #637Provenance
Mined from the project's engine self-play games.
Verified by Stockfish at depth 20+.
Solution forcedness confirmed (verified).
Pack 009 · SP-637
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