Attack on the uncastled king: king to b2 (b1·6)
c9-26896naming 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 b1, queen b4, rook a1, bishop f3 c5, knight g3, pawn c2 g2 h2 c3 d3 a5 f5.
Black: king b8, queen f6, rook e1 a8, bishop g8, knight d6, pawn a6 g6 h6 b7 c7 d7.
13 white and 12 black pieces are on the board; the puzzle position arises after move 16.
The position in numbers
Black are ahead by 1 points of material (30 against 31; pawn = 1, knight and bishop = 3, rook = 5, queen = 9) — the tactic has to convert or outweigh that.
The white king stands on b1, the black king on b8.
It is White to move on move 16, with 2 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 7 pawns, Black 6. Files fully open (no pawns of either colour): e — natural highways for the rooks and queen. Half-open for White: b.
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
16. Kb2 Re5 17. Bd4 Qe7 18. Bxe5 Qxe5 19. fxg6
Why it works
- Great move! king to b2 keeps the pressure (+3.6).
- bishop to d4 develops smoothly.
- Precise: bishop to e5 is the top choice (+3.3).
- Best move. pawn to g6 is exactly what the engine plays (+3.4).
- You win a piece — the rook.
- If instead Re5, then Bd4 and you stay on top.
Move by move
- 16. Kb2 — king to b2
- Re5 — rook to e5
- 17. Bd4 — bishop to d4
- Qe7 — queen to e7
- 18. Bxe5 — bishop to e5 (capture)
- Qxe5 — queen to e5 (capture)
- 19. fxg6 — pawn to g6 (capture)
Types in this puzzle
Relative pin
A piece shields a more valuable one behind it — moving it loses material.
In a relative pin the piece shields not its king but something valuable behind it, usually the queen. Moving is legal but costly, because the piece behind falls. Look for three units on one line: your long-range piece, a cheaper enemy piece, and an expensive one hiding behind. Beware the classic trap — a relatively pinned piece can still move with check or a bigger threat, so verify before you cash in.
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.
Discovered attack
A piece steps aside and opens a second attack from the piece behind it.
A discovered attack works like a curtain: one piece steps off the line and unveils the long-range piece behind it. The beauty is that the moving piece can create a second threat of its own — two attacks in one move. Look for your stacked pairs: a bishop or rook behind a knight or pawn, aimed through them at something valuable. Send the front piece to the most aggressive square — a discovery without a second threat wastes half its power.
About this position
These pieces come from starting position #845.
SP-845 · RampartScout — King on b or g with a knight already on the edge — the least common of the position families (72 in all).
The king starts on b1, the rooks on a1 and e1, the queen on f1.
From b1 the king makes the longest journey Chess960 allows when castling short: five squares to g1.
The bishops stand on d1 and g1; their long diagonals reach h5 and a7 once the e- and f-pawns step aside.
One second-rank pawn starts with no defender at all: d2.
The setup belongs to the RampartScout family; read right to left it becomes position 120.
The engine's main line opens with e4, putting a pawn straight into the centre.
Morozov Balance Index: 5 of 100 — class D — largest edge. Engine evaluation of the starting position: +49 centipawns for White (depth 46, 400 000 000 nodes).
Explore position #845Provenance
Mined from the project's engine self-play games.
Pack 010 · SP-845
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