Mate in 3: queen to f6 (a1·5)
c9-21825naming 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 e1, queen a1, rook b1 h1, bishop d1 e7, knight e4, pawn e2 f2 f3 c4 c5 b6.
Black: king f7, queen a8, rook b8 h8, bishop c7, knight f5, pawn a6 d6 h6.
13 white and 9 black pieces are on the board; the puzzle position arises after move 20.
The position in numbers
White are ahead by 6 points of material (34 against 28; pawn = 1, knight and bishop = 3, rook = 5, queen = 9) — the tactic has to convert or outweigh that.
The white king stands on e1, the black king on f7.
It is White to move on move 20, with 48 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 6 pawns, Black 3. Files fully open (no pawns of either colour): g — natural highways for the rooks and queen. Half-open for White: a, d, 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. Qf6+ Kg8 21. Rg1+ Ng3 22. Qg6#
Why it works
- Best move. queen to f6 is exactly what the engine plays (#2).
- Spot on — rook to g1 (#1).
- Precise: queen to g6 is the top choice (#).
- The line ends in a forced mate in 3.
- If instead Kg8, then Rg1+ and you stay on top.
Move by move
- 20. Qf6+ — queen to f6 with check
- Kg8 — king to g8
- 21. Rg1+ — rook to g1 with check
- Ng3 — knight to g3
- 22. Qg6# — queen to g6 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.
Royal fork
A fork with check: the king must move, and the second piece is lost.
A royal fork is a fork with check — one of the two targets is the king itself. The check must be answered first, so nobody is left to rescue the second piece. Look for squares where your piece gives check and simultaneously attacks an undefended queen or rook. It is the most reliable fork of all, because your opponent literally has no choice.
About this position
These pieces come from starting position #677.
SP-677 · ThroneGuard — King home on d or e, knights kept off the a- and h-files — the family of the standard starting array.
The king starts on e1, the rooks on b1 and h1, the queen on a1.
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 c1 and d1; their long diagonals reach h6 and h5 once the d- and e-pawns step aside.
One second-rank pawn starts with no defender at all: g2.
The setup belongs to the ThroneGuard family; read right to left it becomes position 474.
The engine's main line opens with b4.
Morozov Balance Index: 59 of 100 — class B — balanced. Engine evaluation of the starting position: +24 centipawns for White (depth 47, 400 000 000 nodes).
Explore position #677Provenance
Mined from the project's engine self-play games.
Pack 014 · SP-677
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