Winning blow: bishop to a7 (d4)
c9-09644naming 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 1060 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 g2, rook b3, bishop a2 d4, pawn e2 g3 h4 b7.
Black: king h7, rook d8, bishop a7, knight g4 f5, pawn e4 h5 f7.
8 white and 8 black pieces are on the board; the puzzle position arises after move 27.
The position in numbers
Black are ahead by 2 points of material (15 against 17; pawn = 1, knight and bishop = 3, rook = 5, queen = 9) — the tactic has to convert or outweigh that.
The white king stands on g2, the black king on h7.
It is White to move on move 27, with 33 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 4 pawns, Black 3. Files fully open (no pawns of either colour): a, c, d — natural highways for the rooks and queen. Half-open for White: f.
White hold the bishop pair, an edge in open lines. 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
27. Bxa7 Kg7 28. Bb1 Re8 29. b8=R
Why it works
- Great move! bishop to a7 keeps the pressure (+5.4).
- bishop to b1 develops smoothly.
- Precise: pawn to b8 is the top choice (+5.2).
- You win a piece — the bishop.
- If instead Kg7, then Bb1 and you win the bishop.
Move by move
- 27. Bxa7 — bishop to a7 (capture)
- Kg7 — king to g7
- 28. Bb1 — bishop to b1
- Re8 — rook to e8
- 29. b8=R — pawn to b8
Types in this puzzle
Underpromotion
Promoting to a knight or rook — not a queen — is the only way to win.
Underpromotion means choosing a knight, rook or bishop instead of a queen — and winning precisely because of it. The usual hero is the knight, which delivers a check or a fork from the promotion square in a way no queen can. A rook is chosen when a fresh queen would produce stalemate. When your pawn reaches the last rank, never promote on autopilot — first ask what the knight can do.
About this position
These pieces come from starting position #144.
SP-144 · RampartGuard — King on the wing (b/g) with both knights on inner files.
The king starts on g1, the rooks on d1 and h1, the queen on f1.
The king already stands on its castled square, so castling short moves only the rook, from h1 to f1.
A bishop starts in the corner on a1: it has a single diagonal, which the b-pawn unlocks, running out to h8.
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 815.
The engine's main line opens with c4.
Morozov Balance Index: 55 of 100 — class B — balanced. Engine evaluation of the starting position: +25 centipawns for White (depth 45, 400 000 000 nodes).
Explore position #144Provenance
Mined from the project's engine self-play games.
Pack 006 · SP-144
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