Winning blow: rook to b7 (b5·3)
c9-10547naming 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 2060 ShuffleRating — expert level — few solve it at first try.
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 h3, rook a1 b5, knight f7 d8, pawn e3 g3 h4.
Black: king g7, pawn a2 h5 g6.
8 white and 4 black pieces are on the board; the puzzle position arises after move 39.
The position in numbers
White are ahead by 16 points of material (19 against 3; pawn = 1, knight and bishop = 3, rook = 5, queen = 9) — the tactic has to convert or outweigh that.
The white king stands on h3, the black king on g7.
It is White to move on move 39, with 34 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 — natural highways for the rooks and queen. Half-open for White: a.
The White king has 2 empty squares to step to right now — the fewer they are, the closer a mating net.
Solution & explanation
Main line
39. Rb7 Kf6 40. Ng5 Ke5 41. Rxa2
Why it works
- Sensible development: rook to b7.
- knight to g5 develops smoothly.
- Precise: rook to a2 is the top choice (#3).
- You win decisive material (+15.0).
- If instead g5, then Nxg5+ and you stay on top.
Move by move
- 39. Rb7 — rook to b7
Types in this puzzle
Quiet move
No check, no capture — yet this modest move decides the game.
A quiet move gives no check and takes nothing — yet it decides the game by creating an unstoppable threat or stealing the king's last square. This is the hardest class of moves: the eye hunts for loud blows while a modest shift does the winning. The clue: every forcing try runs into a defense, so seek the move that strengthens the threat or takes squares away. Train yourself to ask: what if I neither capture nor check, but quietly improve?
About this position
These pieces come from starting position #412.
SP-412 · BastionGuard — Both knights begin inside the board while the king stands on c or f; a position and its mirror twin share this family.
The king starts on f1, the rooks on a1 and h1, the queen on c1.
Castling ends where it always does: king to g1 and rook to f1 on the short side, king to c1 and rook to d1 on the long one.
The bishops stand on b1 and g1; their long diagonals reach h7 and a7 once the c- and f-pawns step aside.
The pawn on e2 is defended by the king alone — the same soft spot f2 is in the classical setup.
The setup belongs to the BastionGuard family; read right to left it becomes position 748.
The engine's main line opens with d4, putting a pawn straight into the centre.
Morozov Balance Index: 65 of 100 — class B — balanced. Engine evaluation of the starting position: +22 centipawns for White (depth 46, 400 000 000 nodes).
Explore position #412Provenance
Mined from the project's engine self-play games.
Pack 015 · SP-412
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