Attack on the uncastled king: bishop to b3 (c2·4)
c9-22854naming 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, rook a1 h1, bishop c2 e3, knight f5, pawn b2 e2 g2 h2 a4 e4.
Black: king c8, rook a8 g8, bishop f7, knight b3 c7, pawn a5 f6 b7 e7 g7 h7.
12 white and 12 black pieces are on the board; the puzzle position arises after move 16.
The position in numbers
Material is level — 25 points of pieces on each side (pawn = 1, knight and bishop = 3, rook = 5, queen = 9).
The white king stands on c1, the black king on c8.
It is White to move on move 16, 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 6 pawns, Black 6. Files fully open (no pawns of either colour): c, d — natural highways for the rooks and queen. Half-open for White: f.
White hold the bishop pair, an edge in open lines. 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
16. Bxb3 Bxb3 17. Ra3 Bc4 18. Nxe7+ Kd7 19. Nxg8
Why it works
- Great move! bishop to b3 keeps the pressure (+4.6).
- rook to a3 develops smoothly.
- Precise: knight to e7 is the top choice (+4.9).
- Great move! knight to g8 keeps the pressure (+5.0).
- You win a piece — the rook.
- If instead Bxb3, then Ra3 and you stay on top.
Move by move
- 16. Bxb3 — bishop to b3 (capture)
- Bxb3 — bishop to b3 (capture)
- 17. Ra3 — rook to a3
- Bc4 — bishop to c4
- 18. Nxe7+ — knight to e7 (capture) with check
- Kd7 — king to d7
- 19. Nxg8 — knight to g8 (capture)
Types in this puzzle
Royal fork
A fork with check: the king must move, and the second piece is lost.
A royal fork is a fork with check — one of the two targets is the king itself. The check must be answered first, so nobody is left to rescue the second piece. Look for squares where your piece gives check and simultaneously attacks an undefended queen or rook. It is the most reliable fork of all, because your opponent literally has no choice.
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 #712.
SP-712 · BastionGuard — Both knights begin inside the board while the king stands on c or f; a position and its mirror twin share this family.
The king starts on c1, the rooks on a1 and h1, the queen on d1.
The king already stands on c1, so castling long moves only the rook, from a1 to d1.
The bishops stand on b1 and e1; their long diagonals reach h7 and a5 once the c- and d-pawns step aside.
One second-rank pawn starts with no defender at all: g2.
The setup belongs to the BastionGuard family; read right to left it becomes position 445.
The engine's main line opens with c4.
Morozov Balance Index: 37 of 100 — class C — noticeable edge. Engine evaluation of the starting position: +30 centipawns for White (depth 45, 400 000 000 nodes).
Explore position #712Provenance
Mined from the project's engine self-play games.
Pack 008 · SP-712
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