Attack on the uncastled king: knight to b6 (c4)
c9-10875naming 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.
A fork made possible by the Chess960 piece placement.
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 920 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.
A set-up fork needs one preparing move before the fork lands — a check that drives the king onto the forking square, or a capture that lines the targets up. Find the preparation first, then the fork it makes possible.
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 a4, rook a1 f1, bishop e3, knight c4, pawn a2 b2 e2 g3 h3 d4 f4.
Black: king c8, queen d7, rook a8 f8, bishop f7 h8, knight c2, pawn e4 a5 b6 d6 e6 g6 h7.
13 white and 14 black pieces are on the board; the puzzle position arises after move 18.
The position in numbers
Black are ahead by 3 points of material (32 against 35; 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 18, with 36 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 7 pawns, Black 7. Files fully open (no pawns of either colour): c — natural highways for the rooks and queen.
Black hold the bishop pair, an edge in open lines. The White king has 5 empty squares to step to right now — the fewer they are, the closer a mating net.
Solution & explanation
Main line
18. Nxb6+ Kb7 19. Qxd7+
Why it works
- Great move! knight to b6 keeps the pressure (+7.3).
- Spot on — queen to d7 (+7.7).
- You win a piece — the queen.
- If instead Kb7, then Qxd7+ and you win the queen.
Move by move
- 18. Nxb6+ — knight to b6 (capture) with check
- Kb7 — king to b7
- 19. Qxd7+ — queen to d7 (capture) with check
Types in this puzzle
Setup fork
The random setup allows a fork that classical chess never sees.
A setup fork is a double attack that exists only because of the unusual starting squares — in classical chess these targets never stand side by side. Look for pairs of undefended pieces on your opponent's back rank and for squares from which a knight or pawn hits both at once. Such forks usually appear within the first moves, before the pieces disperse. In every new position, note right away which starting pieces are defended by no one.
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.
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 #559.
SP-559 · BastionGuard — The king starts one file off-centre, on c or f, with neither knight in a corner.
The king starts on c1, the rooks on a1 and f1, the queen on e1.
The king already stands on c1, so castling long moves only the rook, from a1 to d1.
A bishop starts in the corner on h1: it has a single diagonal, which the g-pawn unlocks, running out to a8.
The pawn on c2 is defended by the king alone — the same soft spot f2 is in the classical setup.
The setup belongs to the BastionGuard family; read right to left it becomes position 496.
The engine's main line opens with e4, putting a pawn straight into the centre.
Morozov Balance Index: 72 of 100 — class B — balanced. Engine evaluation of the starting position: +20 centipawns for White (depth 43, 400 000 000 nodes).
Explore position #559Provenance
Mined from the project's engine self-play games.
Pack 004 · SP-559
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