Chess960 tactic on a8 (a4)
c9-13008naming 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.
Mate: a forcing sequence that ends the game — the king has no escape.
Mate in 4: a forced checkmate in four moves — every reply is covered.
Difficulty 2120 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 is a forced mating attack. Start from the enemy king: which of its squares are already covered, and which move takes away the rest while keeping the king in check? Forcing moves — checks and captures — are what turn an attack into mate.
A mate in four is a longer forced net: each of your moves is a check or an irresistible threat, and the king is driven step by step to a square where it is finally trapped. Verify that the defender has exactly one reply at every branch.
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 a4, rook a1 d1, bishop f1 d4, knight f3, pawn g2 h2 a3 e3 b4 c6.
Black: king c8, queen e7, rook d8, bishop f4 e6, knight e8, pawn g7 h7.
13 white and 8 black pieces are on the board; the puzzle position arises after move 22.
The position in numbers
White are ahead by 9 points of material (34 against 25; 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 c8.
It is White to move on move 22, with 42 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 6 pawns, Black 2. Files fully open (no pawns of either colour): d, f — natural highways for the rooks and queen.
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
22. Qa8+ Bb8 23. Qa6+ Kc7 24. Qb7+ Kd6 25. Bc5#
Why it works
- Best move. queen to a8 is exactly what the engine plays (#3).
- Spot on — queen to a6 (#2).
- Precise: queen to b7 is the top choice (#1).
- Best move. bishop to c5 is exactly what the engine plays (#).
- The line ends in a forced mate in 4.
- If instead Bb8, then Qa6+ and you stay on top.
Move by move
- 22. Qa8+ — queen to a8 with check
- Bb8 — bishop to b8
- 23. Qa6+ — queen to a6 with check
- Kc7 — king to c7
- 24. Qb7+ — queen to b7 with check
- Kd6 — king to d6
- 25. Bc5# — bishop to c5 and it is checkmate
Types in this puzzle
Double-check mate
Double check leaves only king moves — and there are none.
The double-check mate ends the game with check from two pieces at once, leaving the king with nothing. Neither capturing nor blocking works against a double check — only a king move, and here there is none. Look for a discovered check where the front piece checks too: it may even land on a defended square with total impunity. That is why the double check crowns so many of the most beautiful sacrificial combinations.
Mate in 4+
A long forced mating combination.
Mate in four or longer is a marathon of forcing moves where the grip must never loosen. The tools are the same: checks, double threats and sacrifices that deny the opponent a single free tempo. Do not juggle the whole tree at once — walk the main line all the way to mate first, then verify the side branches. If somewhere the defender finds one quiet move that holds, your very first move was wrong.
Discovered attack
A piece steps aside and opens a second attack from the piece behind it.
A discovered attack works like a curtain: one piece steps off the line and unveils the long-range piece behind it. The beauty is that the moving piece can create a second threat of its own — two attacks in one move. Look for your stacked pairs: a bishop or rook behind a knight or pawn, aimed through them at something valuable. Send the front piece to the most aggressive square — a discovery without a second threat wastes half its power.
About this position
These pieces come from starting position #894.
SP-894 · BastionScout — King off-centre on c or f with a knight starting on the rim (a/h).
The king starts on c1, the rooks on a1 and d1, the queen on b1.
The king already stands on c1, so castling long moves only the rook, from a1 to d1.
The bishops stand on f1 and g1; their long diagonals reach a6 and a7 once the e- and f-pawns step aside.
Every pawn on the second rank is defended from the very first move.
The setup belongs to the BastionScout family; read right to left it becomes position 68.
The engine's main line opens with e4, putting a pawn straight into the centre.
Morozov Balance Index: 51 of 100 — class C — noticeable edge. Engine evaluation of the starting position: +26 centipawns for White (depth 44, 400 000 000 nodes).
Explore position #894Provenance
Mined from the project's engine self-play games.
Pack 015 · SP-894
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