Mate in 3: queen to c6 (h1·2)
c9-17384naming 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.
Difficulty 1860 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.
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 h1, rook d1, bishop b4, knight d4, pawn c2 h2 b3 d3 a6.
Black: king b6, queen g4, rook f8, knight c5, pawn d6 h7.
10 white and 6 black pieces are on the board; the puzzle position arises after move 28.
The position in numbers
White are ahead by 6 points of material (25 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 b1, the black king on b6.
It is White to move on move 28, with 36 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 5 pawns, Black 2. Files fully open (no pawns of either colour): e, f, g — natural highways for the rooks and queen.
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
28. Qc6+ Ka7 29. Nb5+ Kb8 30. a7#
Why it works
- Great move! queen to c6 keeps the pressure (#2).
- Spot on — knight to b5 (#1).
- Precise: pawn to a7 is the top choice (#).
- The line ends in a forced mate in 3.
- If instead Ka7, then Nb5+ and you stay on top.
Move by move
- 28. Qc6+ — queen to c6 with check
- Ka7 — king to a7
- 29. Nb5+ — knight to b5 with check
- Kb8 — king to b8
- 30. a7# — pawn to a7 and it is checkmate
Types in this puzzle
Pawn mate
The humblest soldier delivers the final blow.
The pawn mate lets the humblest soldier land the final blow. It happens to a king stuck among its own and enemy pieces: the pawn strikes diagonally from one square away and there is nowhere left to run. The sign: the squares around the king are covered or occupied, and your pawn stands one step from striking distance. Never write pawns out of your attack — their blows are the cheapest and therefore the most humiliating.
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 #531.
SP-531 · ThroneGuard — Both knights start on inner files (b–g) while the king sits centrally on d or e — one of 204 positions filed here.
The king starts on d1, the rooks on b1 and g1, the queen on e1.
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.
A bishop starts in the corner on a1: it has a single diagonal, which the b-pawn unlocks, running out to h8.
The pawn on c2 is defended by the king alone — the same soft spot f2 is in the classical setup.
The setup belongs to the ThroneGuard family; read right to left it becomes position 515.
The engine's main line opens with b3.
Morozov Balance Index: 81 of 100 — class A — most balanced. Engine evaluation of the starting position: +13 centipawns for White (depth 47, 400 000 000 nodes).
In 50 self-play games White scored 54.0% (95% CI 40.4–67.0%).
Explore position #531Provenance
Mined from the project's engine self-play games.
Pack 013 · SP-531
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