Attack on the uncastled king: bishop to c6 (d5·8)
c9-25594naming 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 1630 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 c2, rook d1 e3, bishop d5, knight c3, pawn g2 b3 a4 f5 f6.
Black: king d8, queen g3, rook a8 e8, bishop c6, knight f3, pawn a5 g5 b7 c7 f7.
10 white and 11 black pieces are on the board; the puzzle position arises after move 29.
The position in numbers
Black are ahead by 9 points of material (21 against 30; pawn = 1, knight and bishop = 3, rook = 5, queen = 9) — the tactic has to convert or outweigh that.
The white king stands on c2, the black king on d8.
It is White to move on move 29, with 36 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 5 pawns, Black 5. Files fully open (no pawns of either colour): d, e, h — 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
29. Bxc6+ Nd4+ 30. Rxd4+ Kc8 31. Rxe8#
Why it works
- Great move! bishop to c6 keeps the pressure (#2).
- Well found: rook to d4 (#1).
- Strong! rook to e8 is the sharp choice (#).
- The line ends in a forced mate in 3.
- If instead Nd4+, then Rxd4+ and you win the bishop.
Move by move
- 29. Bxc6+ — bishop to c6 (capture) with check
- Nd4+ — knight to d4 with check
- 30. Rxd4+ — rook to d4 (capture) with check
- Kc8 — king to c8
- 31. Rxe8# — rook to e8 (capture) and it is checkmate
Types in this puzzle
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.
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.
Bishop fork
The bishop attacks two pieces on crossing diagonals at once.
A bishop fork happens when the bishop lands where two diagonals cross and attacks a target on each of them. Both victims must stand on the bishop's color — that is the first thing to verify. Scan for loose enemy pieces that share the color of squares with their own king or queen. A common sin is placing your own pieces on squares of one color and handing your opponent exactly this geometry.
About this position
These pieces come from starting position #916.
SP-916 · 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 a1 and e1, the queen on f1.
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.
One second-rank pawn starts with no defender at all: h2.
The setup belongs to the ThroneScout family; read right to left it becomes position 46.
The engine's main line opens with e4, putting a pawn straight into the centre.
Morozov Balance Index: 34 of 100 — class C — noticeable edge. Engine evaluation of the starting position: +31 centipawns for White (depth 48, 400 000 000 nodes).
Explore position #916Provenance
Mined from the project's engine self-play games.
Pack 012 · SP-916
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