Winning blow: rook to c8 (a8·2)
c9-23941naming 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.
A fork made possible by the Chess960 piece placement.
Winning tactic: there is a move that gains a decisive advantage — find it.
Difficulty 1420 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.
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 d1, queen f5, rook e1 a8, bishop c1 f1, knight h1 b3, pawn c2 d2 g2 h2 f3 f4.
Black: king c6, queen a2, bishop a3, knight h8, pawn b7 d7 g7 h7.
14 white and 8 black pieces are on the board; the puzzle position arises after move 18.
The position in numbers
White are ahead by 18 points of material (37 against 19; pawn = 1, knight and bishop = 3, rook = 5, queen = 9) — the tactic has to convert or outweigh that.
The white king stands on d1, the black king on c6.
It is White to move on move 18, with 59 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 6 pawns, Black 4. Files fully open (no pawns of either colour): a, e — natural highways for the rooks and queen. Half-open for White: b.
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
18. Rc8+ Kb6 19. Qa5#
Why it works
- Best move. rook to c8 is exactly what the engine plays (#1).
- Spot on — queen to a5 (#).
- The line ends in a forced mate in 2.
- If instead Kb6, then Qa5# and it is mate.
Move by move
- 18. Rc8+ — rook to c8 with check
- Kb6 — king to b6
- 19. Qa5# — queen to a5 and it is checkmate
Types in this puzzle
Supported queen mate
The queen delivers mate face to face, protected by a friend.
The supported queen mate is the most common pattern of all: the queen lands next to the king and mates because a friendly piece or pawn protects her. The king is helpless — capturing is impossible, and the queen covers every neighboring square herself. Hunt for a protected square beside the enemy king: a knight, bishop or pawn eyeing it turns her invasion into mate. Verify one thing — that the square really is defended, or the king eats her.
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.
Mate in 2
A forced checkmate in two moves.
Mate in two: your move, any reply, then the mating blow. Start with the most forcing first moves — checks and sacrifices that shrink the opponent's options to almost nothing. Against every single reply you must have a mate ready, so check them all without exception. The common failure is analyzing the pretty defense and forgetting the boring one.
About this position
These pieces come from starting position #358.
SP-358 · ThroneScout — A knight starts on the edge (a/h) and the king sits centrally on d or e; the mirror twin stays in this family too.
The king starts on d1, the rooks on b1 and e1, 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 c1 and f1; their long diagonals reach h6 and a6 once the d- and e-pawns step aside.
One second-rank pawn starts with no defender at all: a2.
The setup belongs to the ThroneScout family; read right to left it becomes position 310.
The engine's main line opens with f3.
Morozov Balance Index: 7 of 100 — class D — largest edge. Engine evaluation of the starting position: +46 centipawns for White (depth 46, 400 000 000 nodes).
Explore position #358Provenance
Mined from the project's engine self-play games.
Pack 010 · SP-358
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