Attack on the uncastled king: pawn to b7 (c6·7)
c9-12529naming 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 c1, queen a6, rook b1 h1, bishop a1 d1, knight d3, pawn c2 d2 e2 g2 h2 b3 f3 c6.
Black: king c8, queen g8, rook b8 h8, bishop b7 d8, knight b6 e6, pawn a5 e5 f6 d7 g7 h7.
15 white and 14 black pieces are on the board; the puzzle position arises after move 11.
The position in numbers
Black are ahead by 1 points of material (36 against 37; pawn = 1, knight and bishop = 3, rook = 5, queen = 9) — the tactic has to convert or outweigh that.
The white king stands on c1, the black king on c8.
It is White to move on move 11, with 36 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 8 pawns, Black 6. No file is fully open, so the heavy pieces have to be pried in. Half-open for White: a.
The White king has 1 empty squares to step to right now — the fewer they are, the closer a mating net.
Solution & explanation
Main line
11. cxb7+ Rxb7 12. e3 a4 13. Be2 Nc7 14. Qa5
Why it works
- Great move! pawn to b7 keeps the pressure (+2.7).
- pawn to e3 develops smoothly.
- A natural move: bishop to e2.
- Great move! queen to a5 keeps the pressure (+3.4).
- You reach a winning position (+3.4).
- If instead Rxb7, then e3 and you stay on top.
Move by move
- 11. cxb7+ — pawn to b7 (capture) with check
- Rxb7 — rook to b7 (capture)
- 12. e3 — pawn to e3
- a4 — pawn to a4
- 13. Be2 — bishop to e2
- Nc7 — knight to c7
- 14. Qa5 — queen to a5
Types in this puzzle
Win the pinned piece
The pinned piece cannot run — attack it again and win it.
A pinned piece cannot flee, which means you can win it outright by attacking it one more time. Count attackers against defenders: if you outnumber them, the piece is yours. The best extra attacker is a pawn, since it costs less than anything it might capture. Do not rush the capture — build up the pressure first, then harvest.
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.
Counter-strike
Don't defend — answer the threat with a bigger one.
The counter-strike: instead of defending against the threat, you answer with a bigger threat of your own. While your opponent grabs a pawn, you deliver mate — the arithmetic favors you. Look for a counter when direct defenses fail: do you have a check, an attack on the queen, a mating threat? The beginner's error is meeting every threat with a reflexive defense without checking the counterattacking resources first.
About this position
These pieces come from starting position #737.
SP-737 · BastionGuard — Off-centre king (c/f), no knight on the a- or h-file.
The king starts on c1, the rooks on b1 and h1, the queen on g1.
The king already stands on c1, so castling long moves only the rook, from b1 to d1.
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: a2.
The setup belongs to the BastionGuard family; read right to left it becomes position 411.
The engine's main line opens with b3.
Morozov Balance Index: 80 of 100 — class A — most balanced. Engine evaluation of the starting position: +17 centipawns for White (depth 44, 400 000 000 nodes).
Explore position #737Provenance
Mined from the project's engine self-play games.
Pack 008 · SP-737
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