Attack on the uncastled king: pawn to a3 (b2·32)
c9-12372naming 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 b1, queen c1, rook e2, bishop g1 g2, knight f2 d3, pawn b2 c2 f4 g4 a5.
Black: king b8, queen g6, rook a8, bishop c4, knight a3 d4, pawn h5 a6 f6 b7 c7.
12 white and 11 black pieces are on the board; the puzzle position arises after move 25.
The position in numbers
White are ahead by 3 points of material (31 against 28; 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 25, 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 5 pawns, Black 5. Files fully open (no pawns of either colour): d, e — natural highways for the rooks and queen. Half-open for White: h.
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
25. bxa3 Nxe2 26. Qb2 Bb5 27. a4 Qe8 28. axb5
Why it works
- Great move! pawn to a3 keeps the pressure (+3.6).
- queen to b2 develops smoothly.
- A natural move: pawn to a4.
- Best move. pawn to b5 is exactly what the engine plays (+4.5).
- You reach a winning position (+4.5).
- If instead Nxe2, then Qb2 and you stay on top.
Move by move
- 25. bxa3 — pawn to a3 (capture)
- Nxe2 — knight to e2 (capture)
- 26. Qb2 — queen to b2
- Bb5 — bishop to b5
- 27. a4 — pawn to a4
- Qe8 — queen to e8
- 28. axb5 — pawn to b5 (capture)
Types in this puzzle
Remove the defender
Capture the guard first — then take what it protected.
Removing the defender is the straightforward plan: capture the guard first, then take what it guarded. Unlike deflection, the defender is not lured away — it is traded off or destroyed on the spot. Stare at the target you crave and ask who defends it, and whether that defender can be profitably eaten. Count the whole capture sequence, not just the first move — the trade must pay off at the end.
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.
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 #829.
SP-829 · RampartScout — A wing-file king (b or g) and at least one corner knight: the rarest of the six families, just 72 positions.
The king starts on b1, the rooks on a1 and f1, the queen on e1.
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: g2.
The setup belongs to the RampartScout family; read right to left it becomes position 136.
The engine's main line opens with f4.
Morozov Balance Index: 24 of 100 — class D — largest edge. Engine evaluation of the starting position: +35 centipawns for White (depth 47, 400 000 000 nodes).
Explore position #829Provenance
Mined from the project's engine self-play games.
Pack 007 · SP-829
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