Mate in 2: queen to d6 (c5·4)
c9-11271naming 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.
Difficulty 1450 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.
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 c5, rook a1 f1, bishop b1 f4, pawn b2 d2 g2 a4 f5.
Black: king d7, queen g5, rook a8 e8, bishop d5, knight h8, pawn c6 f6 a7 b7 g7 h7.
11 white and 12 black pieces are on the board; the puzzle position arises after move 20.
The position in numbers
Black are ahead by 1 points of material (30 against 31; pawn = 1, knight and bishop = 3, rook = 5, queen = 9) — the tactic has to convert or outweigh that.
The white king stands on g1, the black king on d7.
It is White to move on move 20, with 47 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 5 pawns, Black 6. Files fully open (no pawns of either colour): e — natural highways for the rooks and queen. Half-open for White: c, h.
White hold the bishop pair, an edge in open lines. 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
20. Qd6+ Kc8 21. Qc7#
Why it works
- Great move! queen to d6 keeps the pressure (#1).
- Well found: queen to c7 (#).
- The line ends in a forced mate in 2.
- If instead Kc8, then Qc7# and it is mate.
Move by move
- 20. Qd6+ — queen to d6 with check
- Kc8 — king to c8
- 21. Qc7# — queen to c7 and it is checkmate
Types in this puzzle
Supported queen mate
The queen delivers mate face to face, protected by a friend.
The supported queen mate is the most common pattern of all: the queen lands next to the king and mates because a friendly piece or pawn protects her. The king is helpless — capturing is impossible, and the queen covers every neighboring square herself. Hunt for a protected square beside the enemy king: a knight, bishop or pawn eyeing it turns her invasion into mate. Verify one thing — that the square really is defended, or the king eats her.
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 #620.
SP-620 · ThroneScout — The king starts on d or e while at least one knight begins in a corner.
The king starts on e1, the rooks on a1 and f1, the queen on d1.
The kingside rook already stands on f1, so castling short moves only the king, from e1 to g1.
The bishops stand on b1 and g1; their long diagonals reach h7 and a7 once the c- and f-pawns step aside.
The second rank carries 2 pawns with no defender at all: b2, g2.
The setup belongs to the ThroneScout family; read right to left it becomes position 252.
The engine's main line opens with f4.
Morozov Balance Index: 1 of 100 — class D — largest edge. Engine evaluation of the starting position: +63 centipawns for White (depth 43, 400 000 000 nodes).
In 50 self-play games White scored 62.0% (95% CI 48.2–74.1%).
Explore position #620Provenance
Mined from the project's engine self-play games.
Pack 011 · SP-620
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