Winning blow: queen to b7 (b5·7)
c9-12414naming 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 in 4: a forced checkmate in four moves — every reply is covered.
A fork made possible by the Chess960 piece placement.
Winning tactic: there is a move that gains a decisive advantage — find it.
Difficulty 2400 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.
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.
A set-up fork needs one preparing move before the fork lands — a check that drives the king onto the forking square, or a capture that lines the targets up. Find the preparation first, then the fork it makes possible.
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 b1, queen b5, rook a1, bishop e1 c6, knight d5 f6, pawn b2 c2 d2 h2 e3 a4 e5.
Black: king d8, queen h8, rook a8, knight e6 d7, pawn h4 a5 f7.
14 white and 8 black pieces are on the board; the puzzle position arises after move 29.
The position in numbers
White are ahead by 10 points of material (33 against 23; pawn = 1, knight and bishop = 3, rook = 5, queen = 9) — the tactic has to convert or outweigh that.
The white king stands on b1, the black king on d8.
It is White to move on move 29, with 43 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): g — 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 2 empty squares to step to right now — the fewer they are, the closer a mating net.
Solution & explanation
Main line
29. Qb7 Ra7 30. Qxa7 Kc8 31. Bxd7+ Kd8 32. Qb8#
Why it works
- Great move! queen to b7 keeps the pressure (#3).
- Well found: queen to a7 (#2).
- Precise: bishop to d7 is the top choice (#1).
- Best move. queen to b8 is exactly what the engine plays (#).
- The line ends in a forced mate in 4.
- If instead Ra7, then Qxa7 and you win the rook.
Move by move
- 29. Qb7 — queen to b7
- Ra7 — rook to a7
- 30. Qxa7 — queen to a7 (capture)
- Kc8 — king to c8
- 31. Bxd7+ — bishop to d7 (capture) with check
- Kd8 — king to d8
- 32. Qb8# — queen to b8 and it is checkmate
Types in this puzzle
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.
Setup fork
The random setup allows a fork that classical chess never sees.
A setup fork is a double attack that exists only because of the unusual starting squares — in classical chess these targets never stand side by side. Look for pairs of undefended pieces on your opponent's back rank and for squares from which a knight or pawn hits both at once. Such forks usually appear within the first moves, before the pieces disperse. In every new position, note right away which starting pieces are defended by no one.
Queen fork
The queen lands on a square from which it attacks two targets at once.
The queen strikes along files, ranks and diagonals, so she forks more often than any other piece. Look for a square where the queen attacks two undefended targets at once — most often a check combined with a loose piece. Diagonal blows are especially venomous: a slanting check that also eyes a rook in the corner is the classic of the genre. Remember that both targets must be unprotected, or your «fork» is just a shot into the air.
About this position
These pieces come from starting position #570.
SP-570 · BastionGuard — King off-centre on c or f with both knights on inner files.
The king starts on c1, the rooks on a1 and g1, the queen on h1.
The king already stands on c1, so castling long moves only the rook, from a1 to d1.
The bishops stand on e1 and f1; their long diagonals reach a5 and a6 once the d- and e-pawns step aside.
The pawn on c2 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 485.
The engine's main line opens with g4.
Morozov Balance Index: 20 of 100 — class D — largest edge. Engine evaluation of the starting position: +37 centipawns for White (depth 45, 400 000 000 nodes).
Explore position #570Provenance
Mined from the project's engine self-play games.
Pack 015 · SP-570
Similar puzzles
In your browser or in the Android app. Nothing to install · Free, no ads