Attack on the uncastled king: knight to d1 (e3·2)
c9-25011naming 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.
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 1200 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.
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 g1, rook a1 h1, bishop b1 c1, knight e1 e3, pawn a2 b2 g2 c3 h3 f4 e5.
Black: king g8, queen d1, rook a8 h8, bishop b8 c8, knight f6 f8, pawn h4 c5 b6 a7 e7 f7 g7.
14 white and 15 black pieces are on the board; the puzzle position arises after move 9.
The position in numbers
Black are ahead by 9 points of material (29 against 38; pawn = 1, knight and bishop = 3, rook = 5, queen = 9) — the tactic has to convert or outweigh that.
The white king stands on g1, the black king on g8.
It is White to move on move 9, with 29 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 7 pawns, Black 7. Files fully open (no pawns of either colour): d — natural highways for the rooks and queen.
The White king has 4 empty squares to step to right now — the fewer they are, the closer a mating net.
Solution & explanation
Main line
9. Nxd1 Nd5 10. Be4 Nc7 11. Nf3 a5 12. Bxa8
Why it works
- Great move! knight to d1 keeps the pressure (+2.8).
- bishop to e4 develops smoothly.
- Precise: knight to f3 is the top choice (+2.4).
- Brilliant! The bishop on a8 is a sacrifice that works — you stand better (+2.8).
- You win a piece — the queen.
- If instead Nd5, then Be4 and you win the queen.
Move by move
- 9. Nxd1 — knight to d1 (capture)
- Nd5 — knight to d5
- 10. Be4 — bishop to e4
- Nc7 — knight to c7
- 11. Nf3 — knight to f3
- a5 — pawn to a5
- 12. Bxa8 — bishop to a8 (capture)
Types in this puzzle
First-rank tactic
Pieces still on their starting rank become targets of a first-rank strike.
The first-rank tactic: enemy pieces that never left their starting rank become targets themselves. Standing shoulder to shoulder, they block each other and are often defended by nobody. Look for a strike along the first or eighth rank — a rook or queen that breaks through harvests the undeveloped pieces. The mistake is treating the back rank as a safe "rear area": in Chess960 it can be the most vulnerable place on the board.
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.
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.
About this position
These pieces come from starting position #404.
SP-404 · RampartGuard — A b- or g-file king and two knights on inner files (b–g).
The king starts on g1, the rooks on a1 and h1, the queen on d1.
The king already stands on its castled square, so castling short moves only the rook, from h1 to f1.
The bishops stand on b1 and c1; their long diagonals reach h7 and h6 once the c- and d-pawns step aside.
The pawn on f2 is defended by the king alone — the classic soft spot of the standard setup.
The setup belongs to the RampartGuard family; read right to left it becomes position 750.
The engine's main line opens with e4, putting a pawn straight into the centre.
Morozov Balance Index: 83 of 100 — class A — most balanced. Engine evaluation of the starting position: +16 centipawns for White (depth 47, 400 000 000 nodes).
Explore position #404Provenance
Mined from the project's engine self-play games.
Pack 008 · SP-404
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