Chess960 tactic on b7 (b1)
c9-14130naming 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.
A fork made possible by the Chess960 piece placement.
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.
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.
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.
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 g1, queen b1, rook f1 e3, bishop g5 e6, knight d2, pawn g2 a4 c4 h4.
Black: king e8, queen h5, rook c8 g8, knight g3 e4, pawn a6 d6 g6 h6 b7 e7.
11 white and 12 black pieces are on the board; the puzzle position arises after move 27.
The position in numbers
White are ahead by 1 points of material (32 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 g1, the black king on e8.
It is White to move on move 27, with 51 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 4 pawns, Black 6. Files fully open (no pawns of either colour): f — natural highways for the rooks and queen. Half-open for White: b, d, e.
White hold the bishop pair, an edge in open lines. The White king has 1 empty squares to step to right now — the fewer they are, the closer a mating net.
Solution & explanation
Main line
27. Qxb7 Ne2+ 28. Rxe2 Rc7 29. Qa8+ Rc8 30. Qxc8#
Why it works
- Great move! queen to b7 keeps the pressure (#3).
- Spot on — rook to e2 (#2).
- Precise: queen to a8 is the top choice (#1).
- Best move. queen to c8 is exactly what the engine plays (#).
- The line ends in a forced mate in 4.
- If instead Ne2+, then Rxe2 and you win the knight.
Move by move
- 27. Qxb7 — queen to b7 (capture)
- Ne2+ — knight to e2 with check
- 28. Rxe2 — rook to e2 (capture)
- Rc7 — rook to c7
- 29. Qa8+ — queen to a8 with check
- Rc8 — rook to c8
- 30. Qxc8# — queen to c8 (capture) 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 #500.
SP-500 · 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 d1.
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 f2 is defended by the king alone — the classic soft spot of the standard setup.
The setup belongs to the BastionGuard family; read right to left it becomes position 558.
The engine's main line opens with c4.
Morozov Balance Index: 96 of 100 — class A — most balanced. Engine evaluation of the starting position: +8 centipawns for White (depth 46, 400 000 000 nodes).
Explore position #500Provenance
Mined from the project's engine self-play games.
Pack 015 · SP-500
Similar puzzles
In your browser or in the Android app. Nothing to install · Free, no ads