Winning blow: rook to a7 (a5·4)
c9-27400naming 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.
Winning tactic: there is a move that gains a decisive advantage — find it.
Difficulty 1290 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.
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 b2, queen g3, rook a5 h8, bishop e3, pawn a2 g2 c3 b4.
Black: king b7, queen d1, rook f5 b6, knight d7, pawn c4 e4 b5 c7.
9 white and 9 black pieces are on the board; the puzzle position arises after move 37.
The position in numbers
Material is level — 26 points of pieces on each side (pawn = 1, knight and bishop = 3, rook = 5, queen = 9).
The white king stands on b2, the black king on b7.
It is White to move on move 37, with 48 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 4 pawns, Black 4. Files fully open (no pawns of either colour): d, f, h — natural highways for the rooks and queen. Half-open for White: e.
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
37. Ra7+ Kc6 38. Qxc7+ Kd5 39. Qxd7+
Why it works
- Great move! rook to a7 keeps the pressure (#4).
- Spot on — queen to c7 (#3).
- Strong! queen to d7 is the sharp choice (#2).
- You win a piece — the knight.
- If instead Kc6, then Qxc7+ and you stay on top.
Move by move
- 37. Ra7+ — rook to a7 with check
- Kc6 — king to c6
- 38. Qxc7+ — queen to c7 (capture) with check
- Kd5 — king to d5
- 39. Qxd7+ — queen to d7 (capture) with check
Types in this puzzle
Skewer
A line attack forces the valuable piece to move, exposing the one behind it.
A skewer is a pin turned inside out: the valuable piece stands in front and something cheaper hides behind it. The big piece must step aside, and you collect the one that was sheltering in its shadow. Scan for the enemy king or queen sharing a file, rank or diagonal with another enemy piece. The deadliest version comes with check — the king moves, the rook behind it dies.
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.
About this position
These pieces come from starting position #929.
SP-929 · BastionScout — King shifted to c or f, with a knight committed to the corner from move one.
The king starts on c1, the rooks on b1 and e1, the queen on g1.
The king already stands on c1, so castling long moves only the rook, from b1 to d1.
A bishop starts in the corner on a1: it has a single diagonal, which the b-pawn unlocks, running out to h8.
One second-rank pawn starts with no defender at all: a2.
The setup belongs to the BastionScout family; read right to left it becomes position 27.
The engine's main line opens with f4.
Morozov Balance Index: 11 of 100 — class D — largest edge. Engine evaluation of the starting position: +42 centipawns for White (depth 47, 400 000 000 nodes).
Explore position #929Provenance
Mined from the project's engine self-play games.
Pack 009 · SP-929
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