Winning blow: bishop to a3 (c1·2)
c9-11708naming 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 1870 ShuffleRating — for advanced tacticians.
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 f1, queen f2, rook a1 g3, bishop c1 d3, knight f3 h6, pawn g2 b3 c3 d4 h4 b5 e5.
Black: king e7, queen d8, rook a8 f8, bishop c7 d7, knight e6, pawn d5 h5 c6 f6 a7 b7.
15 white and 13 black pieces are on the board; the puzzle position arises after move 20.
The position in numbers
White are ahead by 4 points of material (38 against 34; pawn = 1, knight and bishop = 3, rook = 5, queen = 9) — the tactic has to convert or outweigh that.
The white king stands on f1, the black king on e7.
It is White to move on move 20, with 52 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 7 pawns, Black 6. No file is fully open, so the heavy pieces have to be pried in. Half-open for White: a, f.
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
20. Ba3+ c5 21. Bxc5+ Nxc5 22. Rg7+
Why it works
- Great move! bishop to a3 keeps the pressure (#11).
- Well found: bishop to c5 (#10).
- Strong! rook to g7 is the sharp choice (#9).
- You win decisive material (+15.0).
- If instead c5, then Bxc5+ and you stay on top.
Move by move
- 20. Ba3+ — bishop to a3 with check
Types in this puzzle
Winning blow
Find the strike that wins material by force.
A winning blow is a forced material gain that does not fit a single textbook motif. The general tactical recipe applies: spot loose pieces, an awkwardly placed king, overloaded lines. Go through the forcing moves in order of violence — checks, captures, threats — because most combinations start with one of them. Do not judge by feel: calculate the concrete line until the outcome is beyond doubt.
About this position
These pieces come from starting position #452.
SP-452 · BastionGuard — A c- or f-file king and two knights on inner files (b–g).
The king starts on f1, the rooks on a1 and h1, the queen on g1.
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 c1; their long diagonals reach h7 and h6 once the c- and d-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 702.
The engine's main line opens with d4, putting a pawn straight into the centre.
Morozov Balance Index: 40 of 100 — class C — noticeable edge. Engine evaluation of the starting position: +29 centipawns for White (depth 47, 400 000 000 nodes).
Explore position #452Provenance
Mined from the project's engine self-play games.
Pack 014 · SP-452
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