Attack on the uncastled king: pawn to b7 (c6·11)
c9-06671naming 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 1560 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 g1, rook h3, bishop f1 g3, knight h2, pawn b2 f2 g2 a3 d3 h5 c6.
Black: king g8, queen g4, rook a1 h8, bishop f8, knight a8, pawn h6 a7 b7 f7 g7.
12 white and 11 black pieces are on the board; the puzzle position arises after move 17.
The position in numbers
Black are ahead by 9 points of material (21 against 30; pawn = 1, knight and bishop = 3, rook = 5, queen = 9) — the tactic has to convert or outweigh that.
The white king stands on g1, the black king on g8.
It is White to move on move 17, with 18 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 7 pawns, Black 5. Files fully open (no pawns of either colour): e — natural highways for the rooks and queen.
White hold the bishop pair, an edge in open lines. 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
17. cxb7 Rxf1+ 18. Nxf1 Nb6 19. b8=Q
Why it works
- Great move! pawn to b7 keeps the pressure (+3.3).
- Well found: knight to f1 (+3.2).
- Strong! pawn to b8 is the sharp choice (+3.3).
- You win a piece — the rook.
- If instead Rxf1+, then Nxf1 and you win the rook.
Move by move
- 17. cxb7 — pawn to b7 (capture)
- Rxf1+ — rook to f1 (capture) with check
- 18. Nxf1 — knight to f1 (capture)
- Nb6 — knight to b6
- 19. b8=Q — pawn to b8
Types in this puzzle
Promotion
The pawn reaches the last rank and becomes a queen — decisively.
Promotion turns a pawn on the last rank into a queen and rewrites the evaluation on the spot. In tactics the passer rarely walks in for free — usually a sacrifice clears its path. Count the tempi: how many moves does the pawn need, and can the defender stop it in time? And watch the promotion square itself — it must be out of enemy reach or won by force in your combination.
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 #38.
SP-38 · RampartScout — The king starts on b or g while a knight begins on the a- or h-file — the smallest family.
The king starts on g1, the rooks on e1 and h1, the queen on d1.
The king already stands on its castled square, so castling short moves only the rook, from h1 to f1.
The bishops stand on c1 and f1; their long diagonals reach h6 and a6 once the d- and e-pawns step aside.
One second-rank pawn starts with no defender at all: a2.
The setup belongs to the RampartScout family; read right to left it becomes position 918.
The engine's main line opens with c4.
Morozov Balance Index: 93 of 100 — class A — most balanced. Engine evaluation of the starting position: +11 centipawns for White (depth 44, 400 000 000 nodes).
Explore position #38Provenance
Mined from the project's engine self-play games.
Verified by Stockfish at depth 20+.
Solution forcedness confirmed (verified).
Pack 011 · SP-38
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