Attack on the uncastled king: pawn to f3 (f2·5)
c9-08865naming 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 1390 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 e1, rook b1 h2, bishop g1 d5, knight a1, pawn c2 d2 f2 g2 a4 e4 h4 b6.
Black: king c8, queen h5, rook a8 h8, bishop a2 a3, pawn d4 e5 f6 b7 c7 g7 h7.
15 white and 13 black pieces are on the board; the puzzle position arises after move 15.
The position in numbers
White are ahead by 4 points of material (36 against 32; 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 c8.
It is White to move on move 15, with 3 legal replies to weigh — only the line that keeps the advantage solves the puzzle. White are in check right now, so every reply must answer the check.
White keeps 8 pawns, Black 7. No file is fully open, so the heavy pieces have to be pried in.
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
15. f3 Bxb1 16. Ke2 Ba2 17. Bxa2 Rxa4 18. bxc7
Why it works
- Great move! pawn to f3 keeps the pressure (+2.5).
- king to e2 develops smoothly.
- Precise: bishop to a2 is the top choice (+2.6).
- Best move. pawn to c7 is exactly what the engine plays (+2.1).
- You reach a winning position (+2.1).
- If instead Bxb1, then Ke2 and you stay on top.
Move by move
- 15. f3 — pawn to f3
- Bxb1 — bishop to b1 (capture)
- 16. Ke2 — king to e2
- Ba2 — bishop to a2
- 17. Bxa2 — bishop to a2 (capture)
- Rxa4 — rook to a4 (capture)
- 18. bxc7 — pawn to c7 (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.
Blocking save
Block the check with tempo — and turn the game around.
The blocking save: you interpose a piece against the check — not passively, but with tempo, so the blocker creates a threat of its own. Such a block turns defense into attack. Whenever you are checked, compare all three replies — capture, move the king, interpose — and among the interpositions hunt for the one that counterattacks. The mistake is automatically stepping aside with the king when an active block would have turned the game around.
About this position
These pieces come from starting position #270.
SP-270 · BastionScout — King off-centre on c or f with a knight starting on the rim (a/h).
The king starts on c1, the rooks on b1 and h1, the queen on e1.
The king already stands on c1, so castling long moves only the rook, from b1 to d1.
The bishops stand on f1 and g1; their long diagonals reach a6 and a7 once the e- and f-pawns step aside.
One second-rank pawn starts with no defender at all: a2.
The setup belongs to the BastionScout family; read right to left it becomes position 596.
The engine's main line opens with f3.
Morozov Balance Index: 93 of 100 — class A — most balanced. Engine evaluation of the starting position: +11 centipawns for White (depth 48, 400 000 000 nodes).
Explore position #270Provenance
Mined from the project's engine self-play games.
Pack 010 · SP-270
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