Castling-960 to the rescue on a1 (b1·10)
c9-22301naming 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.
Winning tactic: there is a move that gains a decisive advantage — find it.
Difficulty 1920 ShuffleRating — for advanced tacticians.
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.
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 b7, rook a1, bishop e4, knight g3, pawn a2 h2 e6.
Black: king d6, rook a6 e8, bishop h3 g7, knight f8, pawn a3 e5 h7.
8 white and 9 black pieces are on the board; the puzzle position arises after move 25.
The position in numbers
White are ahead by 1 points of material (23 against 22; 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 d6.
It is White to move on move 25, with 36 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 3 pawns, Black 3. Files fully open (no pawns of either colour): b, c, d, f, g — natural highways for the rooks and queen.
Black hold the bishop pair, an edge in open lines. The White king has 3 empty squares to step to right now — the fewer they are, the closer a mating net.
Solution & explanation
Main line
25. O-O-O+ Kxe6 26. Bd5+ Kf6 27. Qf7+ Kg5 28. Qh5+
Why it works
- Great move! king to c1 keeps the pressure (#8).
- Well found: bishop to d5 (#7).
- Precise: queen to f7 is the top choice (#6).
- Great move! queen to h5 keeps the pressure (#5).
- You win decisive material (+15.0).
- If instead Kxe6, then Bd5+ and you stay on top.
Move by move
- 25. O-O-O+ — king to a1 with check
- Kxe6 — king to e6 (capture)
- 26. Bd5+ — bishop to d5 with check
- Kf6 — king to f6
- 27. Qf7+ — queen to f7 with check
- Kg5 — king to g5
- 28. Qh5+ — queen to h5 with check
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.
Check chase
Every move is a check — the king is chased into losing ground.
In a check chase every one of your moves is a check, so the opponent never gets a free second. The king is herded across the board until it loses a piece or walks into a decisive blow. Such lines are the easiest to calculate: each check allows only a handful of replies, so try them all. Make it a habit to start calculating any sharp position with the checks — they are the most forcing moves on the board.
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 #815.
SP-815 · RampartGuard — A wing king (b/g) with no knight on the a- or h-file.
The king starts on b1, the rooks on a1 and e1, the queen on c1.
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.
Every pawn on the second rank is defended from the very first move.
The setup belongs to the RampartGuard family; read right to left it becomes position 144.
The engine's main line opens with g3.
Morozov Balance Index: 21 of 100 — class D — largest edge. Engine evaluation of the starting position: +36 centipawns for White (depth 43, 400 000 000 nodes).
Explore position #815Provenance
Mined from the project's engine self-play games.
Pack 014 · SP-815
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