Attack on the uncastled king: queen to g7 (a1·12)
c9-12303naming 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 2: the first move creates an unstoppable threat, the second delivers mate.
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 1320 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.
Mate in two usually opens with a forcing move — a check, a capture or an unstoppable threat — that strips the king of squares or defenders, so the follow-up mate becomes unavoidable. Look for the first move that leaves the opponent only losing replies.
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 g1, queen a1, rook b3 h3, bishop e4, knight h5, pawn a2 c2 f2 g2 e3 d5.
Black: king g8, queen c8, rook b8 h8, knight e8 f8, pawn b6 e6 a7 d7 f7 g7.
12 white and 12 black pieces are on the board; the puzzle position arises after move 15.
The position in numbers
Material is level — 31 points of pieces on each side (pawn = 1, knight and bishop = 3, rook = 5, queen = 9).
The white king stands on g1, the black king on g8.
It is White to move on move 15, with 46 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 6 pawns, Black 6. Files fully open (no pawns of either colour): h — natural highways for the rooks and queen. Half-open for White: b.
The White king has 3 empty squares to step to right now — the fewer they are, the closer a mating net.
Solution & explanation
Main line
15. Qxg7+ Nxg7 16. Nf6#
Why it works
- Great move! queen to g7 keeps the pressure (#1).
- Well found: knight to f6 (#).
- The line ends in a forced mate in 2.
- If instead Nxg7, then Nf6# and it is mate.
Move by move
- 15. Qxg7+ — queen to g7 (capture) with check
- Nxg7 — knight to g7 (capture)
- 16. Nf6# — knight to f6 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 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 #401.
SP-401 · RampartGuard — A wing king (b/g) with no knight on the a- or h-file.
The king starts on g1, the rooks on b1 and h1, the queen on c1.
The king already stands on its castled square, so castling short moves only the rook, from h1 to f1.
A bishop starts in the corner on a1: it has a single diagonal, which the b-pawn unlocks, running out to h8.
One second-rank pawn starts with no defender at all: a2.
The setup belongs to the RampartGuard family; read right to left it becomes position 747.
The engine's main line opens with b4.
Morozov Balance Index: 96 of 100 — class A — most balanced. Engine evaluation of the starting position: -7 centipawns for White (depth 41, 400 000 000 nodes).
In 50 self-play games White scored 49.0% (95% CI 35.7–62.4%).
Explore position #401Provenance
Mined from the project's engine self-play games.
Pack 010 · SP-401
Similar puzzles
In your browser or in the Android app. Nothing to install · Free, no ads