Mate in 3: queen to h8 (g7·3)
c9-25060naming 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.
Difficulty 1630 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.
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 f1, queen g7, rook a1 g1, knight c4 f6, pawn a2 b2 c2 e2 f2 h2 d3 g4.
Black: king d8, queen c7, rook a8 h8, knight b4 b8, pawn c5 e5 e6 g6 a7 b7 h7.
14 white and 13 black pieces are on the board; the puzzle position arises after move 15.
The position in numbers
White are ahead by 1 points of material (33 against 32; pawn = 1, knight and bishop = 3, rook = 5, queen = 9) — the tactic has to convert or outweigh that.
The white king stands on f1, the black king on d8.
It is White to move on move 15, with 47 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 8 pawns, Black 7. No file is fully open, so the heavy pieces have to be pried in.
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
15. Qxh8+ Ke7 16. Qg7+ Kd8 17. Qf8#
Why it works
- Great move! queen to h8 keeps the pressure (#2).
- Spot on — queen to g7 (#1).
- Precise: queen to f8 is the top choice (#).
- The line ends in a forced mate in 3.
- If instead Ke7, then Qg7+ and you win the rook.
Move by move
- 15. Qxh8+ — queen to h8 (capture) with check
- Ke7 — king to e7
- 16. Qg7+ — queen to g7 with check
- Kd8 — king to d8
- 17. Qf8# — queen to f8 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.
Relative pin
A piece shields a more valuable one behind it — moving it loses material.
In a relative pin the piece shields not its king but something valuable behind it, usually the queen. Moving is legal but costly, because the piece behind falls. Look for three units on one line: your long-range piece, a cheaper enemy piece, and an expensive one hiding behind. Beware the classic trap — a relatively pinned piece can still move with check or a bigger threat, so verify before you cash in.
About this position
These pieces come from starting position #427.
SP-427 · BastionGuard — The king starts one file off-centre, on c or f, with neither knight in a corner.
The king starts on f1, the rooks on a1 and g1, the queen on c1.
Castling short simply swaps the two pieces: the king on f1 and the rook on g1 trade places.
A bishop starts in the corner on h1: it has a single diagonal, which the g-pawn unlocks, running out to a8.
One second-rank pawn starts with no defender at all: h2.
The setup belongs to the BastionGuard family; read right to left it becomes position 721.
The engine's main line opens with d3.
Morozov Balance Index: 40 of 100 — class C — noticeable edge. Engine evaluation of the starting position: +29 centipawns for White (depth 43, 400 000 000 nodes).
Explore position #427Provenance
Mined from the project's engine self-play games.
Pack 012 · SP-427
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