Attack on the uncastled king: knight to b7 (c5·20)
c9-24609naming 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 d1, queen h1, rook c1 e1, bishop a6, knight c5, pawn a2 d2 h2 b3 d5.
Black: king d8, queen g7, rook b8 e8, bishop a1, knight f6 f8, pawn b6 g6 a7 d7 h7.
11 white and 12 black pieces are on the board; the puzzle position arises after move 16.
The position in numbers
Black are ahead by 3 points of material (30 against 33; 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 d8.
It is White to move on move 16, with 42 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 5 pawns, Black 5. Files fully open (no pawns of either colour): c, e, f — natural highways for the rooks and queen. Half-open for White: g.
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
16. Nb7+ Rxb7 17. Bxb7 Re5 18. d6 Ke8 19. Rxa1
Why it works
- Great move! knight to b7 keeps the pressure (+3.2).
- Well found: bishop to b7 (+3.2).
- A natural move: pawn to d6.
- Best move. rook to a1 is exactly what the engine plays (+3.2).
- You win a piece — the rook.
- If instead Rxb7, then Bxb7 and you stay on top.
Move by move
- 16. Nb7+ — knight to b7 with check
- Rxb7 — rook to b7 (capture)
- 17. Bxb7 — bishop to b7 (capture)
- Re5 — rook to e5
- 18. d6 — pawn to d6
- Ke8 — king to e8
- 19. Rxa1 — rook to a1 (capture)
Types in this puzzle
Winning blow
Find the strike that wins material by force.
A winning blow is a forced material gain that does not fit a single textbook motif. The general tactical recipe applies: spot loose pieces, an awkwardly placed king, overloaded lines. Go through the forcing moves in order of violence — checks, captures, threats — because most combinations start with one of them. Do not judge by feel: calculate the concrete line until the outcome is beyond doubt.
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.
Uncastled king
The king lingered in the middle — punish the delay.
Punishing the uncastled king: your opponent delayed castling, and now his king is stuck on its starting square under fire. In Chess960 this is deadlier than in classical chess — the king may start in the center or near the edge, and the familiar defensive setups simply do not apply. The signs: the victim still holds castling rights, and the files toward his king are half-open. Open lines before the king manages to hide.
About this position
These pieces come from starting position #944.
SP-944 · ThroneGuard — The king starts in the middle of the back rank, on d or e, and neither knight begins in a corner.
The king starts on d1, the rooks on c1 and e1, the queen on h1.
Castling long simply swaps the two pieces: the king on d1 and the rook on c1 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: f2.
The setup belongs to the ThroneGuard family; read right to left it becomes position 15.
The engine's main line opens with g3.
Morozov Balance Index: 6 of 100 — class D — largest edge. Engine evaluation of the starting position: +48 centipawns for White (depth 46, 400 000 000 nodes).
Explore position #944Provenance
Mined from the project's engine self-play games.
Pack 008 · SP-944
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