Attack on the uncastled king: pawn to b3 (a2·17)
c9-05609naming 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 780 ShuffleRating — for beginners taking their first steps in Chess960 tactics.
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 e1, rook f1 c7, bishop g1, knight b1, pawn a2 d2 e2 f2 h2 g3.
Black: king e8, queen a8, rook f8, bishop b3, pawn e5 f5 g6 a7 b7 h7.
11 white and 10 black pieces are on the board; the puzzle position arises after move 14.
The position in numbers
Black are ahead by 1 points of material (22 against 23; pawn = 1, knight and bishop = 3, rook = 5, queen = 9) — the tactic has to convert or outweigh that.
The white king stands on e1, the black king on e8.
It is White to move on move 14, with 27 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 6 pawns, Black 6. Files fully open (no pawns of either colour): c — natural highways for the rooks and queen. Half-open for White: b.
The White king has 0 empty squares to step to right now — the fewer they are, the closer a mating net.
Solution & explanation
Main line
14. axb3 O-O 15. f4 exf4 16. gxf4
Why it works
- Great move! pawn to b3 keeps the pressure (+2.5).
- pawn to f4 develops smoothly.
- Precise: pawn to f4 is the top choice (+2.6).
- You win a piece — the bishop.
- If instead O-O, then Nc3 and you win the bishop.
Move by move
- 14. axb3 — pawn to b3 (capture)
Types in this puzzle
Hanging piece
A piece is left without protection — just take it.
A hanging piece is simply an unprotected piece you can take for free. It sounds primitive, yet most amateur games are decided exactly this way. Build the habit: before every move, sweep the board and note every undefended piece, yours and theirs. The classic mistake is hunting for a brilliant combination when all you need to do is bend down and pick up the gift.
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 #15.
SP-15 · ThroneGuard — Both knights start on inner files (b–g) while the king sits centrally on d or e — one of 204 positions filed here.
The king starts on e1, the rooks on d1 and f1, the queen on a1.
The kingside rook already stands on f1, so castling short moves only the king, from e1 to g1.
A bishop starts in the corner on h1: it has a single diagonal, which the g-pawn unlocks, running out to a8.
One second-rank pawn starts with no defender at all: c2.
The setup belongs to the ThroneGuard family; read right to left it becomes position 944.
The engine's main line opens with b3.
Morozov Balance Index: 47 of 100 — class C — noticeable edge. Engine evaluation of the starting position: +27 centipawns for White (depth 43, 400 000 000 nodes).
Explore position #15Provenance
Mined from the project's engine self-play games.
Verified by Stockfish at depth 20+.
Solution forcedness confirmed (verified).
Pack 002 · SP-15
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