Attack on the uncastled king: pawn to c7 (c6·4)
c9-24917naming 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 b1, queen f2, rook d1 b3, bishop c1 f1, knight g3 e5, pawn b2 c2 e2 h2 f3 a5 c6.
Black: king b8, queen g8, rook a8 d8, bishop b4 c8, knight f6 g6, pawn d5 h5 a6 e6 b7 g7.
15 white and 14 black pieces are on the board; the puzzle position arises after move 16.
The position in numbers
White are ahead by 1 points of material (38 against 37; 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 b8.
It is White to move on move 16, with 46 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 7 pawns, Black 6. No file is fully open, so the heavy pieces have to be pried in. Half-open for White: d, g.
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
16. c7+ Kxc7 17. Qb6+ Kb8 18. Nc6#
Why it works
- Great move! pawn to c7 keeps the pressure (#2).
- Well found: queen to b6 (#1).
- Strong! knight to c6 is the sharp choice (#).
- The line ends in a forced mate in 3.
- If instead Kxc7, then Qb6+ and you stay on top.
Move by move
- 16. c7+ — pawn to c7 with check
- Kxc7 — king to c7 (capture)
- 17. Qb6+ — queen to b6 with check
- Kb8 — king to b8
- 18. Nc6# — knight to c6 and it is checkmate
Types in this puzzle
Knight mate
The knight lands the killing blow from its unique angle.
In a knight mate the final blow comes from the knight — the only piece whose check can never be blocked. That makes it lethal against a cramped king: only a king move or capturing the knight itself can help. The sign: the squares around the king are occupied or covered, and there is a hop from which the knight checks while staying untouchable. Bring the knight over early — it is slower than the long-range pieces, but its strike cannot be parried.
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 #934.
SP-934 · RampartScout — A knight in the corner and the king out on the wing (b/g); like every family, it is closed under mirror twins.
The king starts on b1, the rooks on a1 and d1, the queen on g1.
From b1 the king makes the longest journey Chess960 allows when castling short: five squares to g1.
The bishops stand on c1 and f1; their long diagonals reach h6 and a6 once the d- and e-pawns step aside.
Every pawn on the second rank is defended from the very first move.
The setup belongs to the RampartScout family; read right to left it becomes position 22.
The engine's main line opens with a4.
Morozov Balance Index: 7 of 100 — class D — largest edge. Engine evaluation of the starting position: +47 centipawns for White (depth 46, 400 000 000 nodes).
Explore position #934Provenance
Mined from the project's engine self-play games.
Pack 012 · SP-934
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