Castling-960 to the rescue on a1 (b1·4)
c9-18672naming tag (square·N)Opens in the app if installed, otherwise downloads the APK.
The tactical motive
Castling 960: the strongest move is to castle — drag the king onto its rook.
Chess960 twist: use the unusual starting setup of the pieces.
Difficulty 1340 ShuffleRating — club-player level.
White to move — find the best continuation
How to recognize this tactic
Chess960 castling still ends with king and rook on the classical squares (g1/f1 or c1/d1), but the path can be unusual. Watch which squares the king crosses and whether castling here opens a file, drops a defender or walks into a 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.
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 e5, rook a1, bishop d3, pawn b2 e2 c3 a4 d4 g4.
Black: king b8, queen h3, rook b6, bishop g6, pawn a5 e6 b7 c7.
10 white and 8 black pieces are on the board; the puzzle position arises after move 31.
The position in numbers
White are ahead by 2 points of material (23 against 21; 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 31, with 35 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 6 pawns, Black 4. Files fully open (no pawns of either colour): f, h — natural highways for the rooks and queen.
The White king has 4 empty squares to step to right now — the fewer they are, the closer a mating net.
Solution & explanation
Main line
31. O-O-O Bxd3 32. Rxd3 Qg2 33. g5
Why it works
- Great move! king to c1 keeps the pressure (+2.9).
- Well found: rook to d3 (+3.1).
- Precise: pawn to g5 is the top choice (+3.3).
- You reach a winning position (+3.3).
- If instead Bxd3, then Rxd3 and you stay on top.
Move by move
- 31. O-O-O — king to a1
Types in this puzzle
Castling to safety
One move — castling — whisks the king out of mortal danger.
Castling to safety: the only escape from the attack is to castle — one move whisks the king to g1 or c1 and brings the rook into play as a bonus. In Chess960 this leap can cross half the board, which is exactly why it slips out of sight. Whenever your king is under pressure, ask first: can I still castle? The typical blunder is throwing that right away with a careless king or rook move.
Winning blow
Find the strike that wins material by force.
A winning blow is a forced material gain that does not fit a single textbook motif. The general tactical recipe applies: spot loose pieces, an awkwardly placed king, overloaded lines. Go through the forcing moves in order of violence — checks, captures, threats — because most combinations start with one of them. Do not judge by feel: calculate the concrete line until the outcome is beyond doubt.
960 castling C-side
Chess960 castling to the C-side — the king lands on c1 wherever it started.
C-side castling in Chess960 sends the king to c1 and the rook to d1, no matter where they began. Sometimes it is one small hop, sometimes a journey through the center — check in advance which squares must be empty and whether any of them are attacked. The rules match classical chess: neither piece has moved, and the king never passes through check. In the game, just drag the king onto the rook.
About this position
These pieces come from starting position #823.
SP-823 · RampartGuard — The king starts out on a wing file, b or g, with neither knight in a corner.
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.
A bishop starts in the corner on h1: it has a single diagonal, which the g-pawn unlocks, running out to a8.
One second-rank pawn starts with no defender at all: h2.
The setup belongs to the RampartGuard family; read right to left it becomes position 130.
The engine's main line opens with a4.
Morozov Balance Index: 100 of 100 — class A — most balanced. Engine evaluation of the starting position: -5 centipawns for White (depth 44, 400 000 000 nodes).
In 50 self-play games White scored 52.0% (95% CI 38.5–65.2%).
Explore position #823Provenance
Mined from the project's engine self-play games.
Pack 010 · SP-823
Similar puzzles
In your browser or in the Android app. Nothing to install · Free, no ads