Winning blow: bishop to b1 (a2)
c9-24243naming 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 1200 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 f2, rook e7, bishop e1 a2, knight d7, pawn c3 g3 a4.
Black: king g6, rook e8 h8, knight h6, pawn b6 a7 h7.
8 white and 7 black pieces are on the board; the puzzle position arises after move 37.
The position in numbers
White are ahead by 1 points of material (17 against 16; pawn = 1, knight and bishop = 3, rook = 5, queen = 9) — the tactic has to convert or outweigh that.
The white king stands on f2, the black king on g6.
It is White to move on move 37, with 32 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): d, e, f — natural highways for the rooks and queen. Half-open for White: b, h.
White hold the bishop pair, an edge in open lines. The White king has 6 empty squares to step to right now — the fewer they are, the closer a mating net.
Solution & explanation
Main line
37. Bb1+ Nf5 38. Rxe8 Rxe8 39. g4 h5 40. Bxf5+
Why it works
- Great move! bishop to b1 keeps the pressure (+5.7).
- Well found: rook to e8 (+5.5).
- A natural move: pawn to g4.
- Best move. bishop to f5 is exactly what the engine plays (+5.9).
- You win a piece — the rook.
- If instead Nf5, then Rxe8 and you win the rook.
Move by move
- 37. Bb1+ — bishop to b1 with check
- Nf5 — knight to f5
- 38. Rxe8 — rook to e8 (capture)
- Rxe8 — rook to e8 (capture)
- 39. g4 — pawn to g4
- h5 — pawn to h5
- 40. Bxf5+ — bishop to f5 (capture) with check
Types in this puzzle
Win the pinned piece
The pinned piece cannot run — attack it again and win it.
A pinned piece cannot flee, which means you can win it outright by attacking it one more time. Count attackers against defenders: if you outnumber them, the piece is yours. The best extra attacker is a pawn, since it costs less than anything it might capture. Do not rush the capture — build up the pressure first, then harvest.
Counter-strike
Don't defend — answer the threat with a bigger one.
The counter-strike: instead of defending against the threat, you answer with a bigger threat of your own. While your opponent grabs a pawn, you deliver mate — the arithmetic favors you. Look for a counter when direct defenses fail: do you have a check, an attack on the queen, a mating threat? The beginner's error is meeting every threat with a reflexive defense without checking the counterattacking resources first.
Trapped piece
The attacked piece has no safe square — it is caught.
Trapping a piece means the attacked piece has no safe square left — it simply perishes. Do not chase it around; build a cage instead: cut off the escape squares with pawns and pieces first, and attack last. The typical victim has wandered deep into your camp or is stuck at the edge of the board, where its mobility is tiny. And always check the way home for your own raiders — or the trapped piece will be yours.
About this position
These pieces come from starting position #504.
SP-504 · BastionGuard — King off-centre on c or f with both knights on inner files.
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 e1; their long diagonals reach h7 and a5 once the c- and d-pawns step aside.
The pawn on g2 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 557.
The engine's main line opens with d4, putting a pawn straight into the centre.
Morozov Balance Index: 8 of 100 — class D — largest edge. Engine evaluation of the starting position: +45 centipawns for White (depth 45, 400 000 000 nodes).
Explore position #504Provenance
Mined from the project's engine self-play games.
Pack 008 · SP-504
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