Winning blow: bishop to a4 (c6)
c9-16800naming 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 c1, queen b6, rook b1 e1, bishop g1 c6, knight e7, pawn a2 c2 d2 h2 g3 b4 f4.
Black: king a8, queen a4, rook b8 d8, bishop g8 h8, knight b7, pawn a3 g7 h7.
14 white and 10 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 (35 against 31; pawn = 1, knight and bishop = 3, rook = 5, queen = 9) — the tactic has to convert or outweigh that.
The white king stands on c1, the black king on a8.
It is White to move on move 20, with 51 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 7 pawns, Black 3. Files fully open (no pawns of either colour): e — natural highways for the rooks and queen.
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
20. Bxa4 Nc5 21. Qa5+ Kb7 22. Bc6#
Why it works
- Best move. bishop to a4 is exactly what the engine plays (#2).
- Spot on — queen to a5 (#1).
- Precise: bishop to c6 is the top choice (#).
- The line ends in a forced mate in 3.
- If instead Nc5, then Qa5+ and you win the queen.
Move by move
- 20. Bxa4 — bishop to a4 (capture)
- Nc5 — knight to c5
- 21. Qa5+ — queen to a5 with check
- Kb7 — king to b7
- 22. Bc6# — bishop to c6 and it is checkmate
Types in this puzzle
Mate in 3
A forced checkmate in three moves.
Mate in three is a forced staircase: each of your moves narrows the opponent's choices, and the third one ends the game. Look for the start among checks and sacrifices — quiet first moves are rare in mating problems, but deliciously sneaky. Keep the tree in your head: every defense gets its own branch. Do not stop calculating after move two — see the final mating picture with your own eyes.
Royal fork
A fork with check: the king must move, and the second piece is lost.
A royal fork is a fork with check — one of the two targets is the king itself. The check must be answered first, so nobody is left to rescue the second piece. Look for squares where your piece gives check and simultaneously attacks an undefended queen or rook. It is the most reliable fork of all, because your opponent literally has no choice.
About this position
These pieces come from starting position #879.
SP-879 · BastionGuard — King shifted to c or f, knights kept clear of the edges — 168 positions in all.
The king starts on c1, the rooks on b1 and d1, the queen on a1.
The king already stands on c1, so castling long moves only the rook, from b1 to d1.
A bishop starts in the corner on h1: it has a single diagonal, which the g-pawn unlocks, running out to a8.
One second-rank pawn starts with no defender at all: e2.
The setup belongs to the BastionGuard family; read right to left it becomes position 80.
The engine's main line opens with b4.
Morozov Balance Index: 1 of 100 — class D — largest edge. Engine evaluation of the starting position: +66 centipawns for White (depth 43, 400 000 000 nodes).
In 50 self-play games White scored 60.0% (95% CI 46.2–72.4%).
Explore position #879Provenance
Mined from the project's engine self-play games.
Pack 006 · SP-879
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