Attack on the uncastled king: queen to f6 (c3·4)
c9-23356naming 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 3: a forced sequence that ends in checkmate.
A fork made possible by the Chess960 piece placement.
Uncastled king: the enemy king is stuck in the centre — punish it before it castles.
Difficulty 1760 ShuffleRating — for advanced tacticians.
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.
In a mate in three every move must be forcing; the defender should never get a free tempo. Find the check or threat that herds the king, calculate the single defence to each, and confirm the net closes on the third move.
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.
An uncastled king in the centre is a standing target. Look for ways to open the central files and diagonals against it with checks and threats before it can shelter — every tempo the king spends in the middle is a chance for a combination.
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 c3, rook a1 h1, knight f3 c5, pawn d2 g2 h2 b4 b5 f5.
Black: king d8, queen b8, rook h8, bishop g8, knight a5, pawn f4 g5 d6 c7 h7.
12 white and 10 black pieces are on the board; the puzzle position arises after move 20.
The position in numbers
White are ahead by 6 points of material (31 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 d8.
It is White to move on move 20, with 48 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 6 pawns, Black 5. Files fully open (no pawns of either colour): a, e — natural highways for the rooks and queen. Half-open for White: c.
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
20. Qf6+ Ke8 21. Re1+ Be6 22. Rxe6#
Why it works
- Best move. queen to f6 is exactly what the engine plays (#2).
- Spot on — rook to e1 (#1).
- Precise: rook to e6 is the top choice (#).
- The line ends in a forced mate in 3.
- If instead Ke8, then Re1+ and you stay on top.
Move by move
- 20. Qf6+ — queen to f6 with check
- Ke8 — king to e8
- 21. Re1+ — rook to e1 with check
- Be6 — bishop to e6
- 22. Rxe6# — rook to e6 (capture) and it is checkmate
Types in this puzzle
Hook mate
Rook, knight and pawn form a hook the king cannot escape.
The hook mate is a three-piece construction: the rook mates, the knight guards the rook, and a pawn guards the knight. The rook strikes the king at close range along a line, the knight stands diagonally nearby stealing the escape squares, and the pawn anchors the chain. The pattern usually appears near the edge after a rook invasion. Build it link by link — first plant the knight under pawn protection, then crash in with the rook.
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 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.
About this position
These pieces come from starting position #238.
SP-238 · 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 h1, the queen on c1.
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 f1 and g1; their long diagonals reach a6 and a7 once the e- and f-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 628.
The engine's main line opens with c4.
Morozov Balance Index: 4 of 100 — class D — largest edge. Engine evaluation of the starting position: +50 centipawns for White (depth 44, 400 000 000 nodes).
Explore position #238Provenance
Mined from the project's engine self-play games.
Pack 013 · SP-238
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