Attack on the uncastled king: pawn to b5 (a4·14)
c9-05240naming 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 a1 f1, bishop h1 d2, knight f3, pawn b2 f2 h2 c3 g3 a4 e5.
Black: king e8, queen b5, rook a8 f8, bishop f5 h8, pawn a5 d5 h6 b7 c7 e7 f7 g7.
13 white and 14 black pieces are on the board; the puzzle position arises after move 13.
The position in numbers
Black are ahead by 7 points of material (26 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 e1, the black king on e8.
It is White to move on move 13, with 26 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: d.
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
13. axb5 Bd3 14. Nd4 g5 15. Bxd5
Why it works
- Great move! pawn to b5 keeps the pressure (+4.2).
- knight to d4 develops smoothly.
- Precise: bishop to d5 is the top choice (+4.2).
- You win a piece — the queen.
- If instead Bd3, then Nd4 and you win the queen.
Move by move
- 13. axb5 — pawn to b5 (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 #615.
SP-615 · 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 a1 and f1, the queen on d1.
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: h2.
The setup belongs to the ThroneGuard family; read right to left it becomes position 242.
The engine's main line opens with c4.
Morozov Balance Index: 94 of 100 — class A — most balanced. Engine evaluation of the starting position: +10 centipawns for White (depth 50, 400 000 000 nodes).
Explore position #615Provenance
Mined from the project's engine self-play games.
Verified by Stockfish at depth 20+.
Solution forcedness confirmed (verified).
Pack 002 · SP-615
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