Mate in 3: queen to g6 (g3·2)
c9-10036naming 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 1990 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 g1, queen g3, rook a1 h6, bishop f5, pawn a2 b2 e2 g2 e3.
Black: king f7, queen e7, knight e4 f6, pawn b5.
10 white and 5 black pieces are on the board; the puzzle position arises after move 26.
The position in numbers
White are ahead by 11 points of material (27 against 16; 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 f7.
It is White to move on move 26, with 45 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 5 pawns, Black 1. Files fully open (no pawns of either colour): c, d, f, h — natural highways for the rooks and queen.
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
26. Qg6+ Kf8 27. Rh8+ Ng8 28. Rxg8#
Why it works
- Best move. queen to g6 is exactly what the engine plays (#2).
- Spot on — rook to h8 (#1).
- Precise: rook to g8 is the top choice (#).
- The line ends in a forced mate in 3.
- If instead Kf8, then Rh8+ and you stay on top.
Move by move
- 26. Qg6+ — queen to g6 with check
- Kf8 — king to f8
- 27. Rh8+ — rook to h8 with check
- Ng8 — knight to g8
- 28. Rxg8# — rook to g8 (capture) 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.
Win the pinned piece
The pinned piece cannot run — attack it again and win it.
A pinned piece cannot flee, which means you can win it outright by attacking it one more time. Count attackers against defenders: if you outnumber them, the piece is yours. The best extra attacker is a pawn, since it costs less than anything it might capture. Do not rush the capture — build up the pressure first, then harvest.
About this position
These pieces come from starting position #516.
SP-516 · BastionGuard — King off-centre on c or f with both knights on inner files.
The king starts on f1, the rooks on a1 and h1, 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.
The bishops stand on b1 and c1; their long diagonals reach h7 and h6 once the c- and d-pawns step aside.
The pawn on g2 is defended by the king alone — the same soft spot f2 is in the classical setup.
The setup belongs to the BastionGuard family; read right to left it becomes position 542.
The engine's main line opens with c4.
Morozov Balance Index: 69 of 100 — class B — balanced. Engine evaluation of the starting position: +21 centipawns for White (depth 45, 400 000 000 nodes).
Explore position #516Provenance
Mined from the project's engine self-play games.
Pack 014 · SP-516
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