Attack on the uncastled king: knight to e6 (d4·16)
c9-21404naming 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.
Uncastled king: the enemy king is stuck in the centre — punish it before it castles.
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.
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.
An uncastled king in the centre is a standing target. Look for ways to open the central files and diagonals against it with checks and threats before it can shelter — every tempo the king spends in the middle is a chance for a combination.
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 f1, queen h3, rook e1 g1, bishop a1 d3, knight d1 d4, pawn a2 d2 e2 f2 g2 c4 h4.
Black: king f8, queen h8, rook e8 g8, bishop a8 b8, knight e7 d8, pawn b4 f5 h5 b6 e6 g6 a7 d7.
15 white and 16 black pieces are on the board; the puzzle position arises after move 9.
The position in numbers
Black are ahead by 1 points of material (38 against 39; pawn = 1, knight and bishop = 3, rook = 5, queen = 9) — the tactic has to convert or outweigh that.
The white king stands on f1, the black king on f8.
It is White to move on move 9, with 34 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 7 pawns, Black 8. No file is fully open, so the heavy pieces have to be pried in. Half-open for White: b.
The White king has 1 empty squares to step to right now — the fewer they are, the closer a mating net.
Solution & explanation
Main line
9. Nxe6+ Nxe6 10. Bxh8
Why it works
- Brilliant! The knight on e6 is a sacrifice that works — you stand better (+2.6).
- Well found: bishop to h8 (+2.4).
- You win a piece — the queen.
- If instead Nxe6, then Bxh8 and you win the queen.
Move by move
- 9. Nxe6+ — knight to e6 (capture) with check
- Nxe6 — knight to e6 (capture)
- 10. Bxh8 — bishop to h8 (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.
Only move
Everything else loses — find the only move that holds.
An only move is a position where everything loses except one single continuation. You cannot play "by hand" here: run through fundamentally different defenses — run away, block, trade, counterattack — and discard the ones that fail. The hallmark of these puzzles is that the obvious moves lose quickly while the solution often looks strange. First understand exactly what the threat is — then the one saving move reveals itself.
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.
About this position
These pieces come from starting position #80.
SP-80 · BastionGuard — A c- or f-file king and two knights on inner files (b–g).
The king starts on f1, the rooks on e1 and g1, the queen on h1.
Castling short simply swaps the two pieces: the king on f1 and the rook on g1 trade places.
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: d2.
The setup belongs to the BastionGuard family; read right to left it becomes position 879.
The engine's main line opens with g4.
Morozov Balance Index: 1 of 100 — class D — largest edge. Engine evaluation of the starting position: +83 centipawns for White (depth 43, 400 000 000 nodes).
In 50 self-play games White scored 56.0% (95% CI 42.3–68.8%).
Explore position #80Provenance
Mined from the project's engine self-play games.
Pack 007 · SP-80
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