Mate in 3: rook to h7 (g7·3)
c9-22118naming 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 f1, queen f6, rook g7, bishop g1, knight e1 f3, pawn a2 b3 d3 e3 f4 h4 h6.
Black: king h8, queen b7, rook c6 e8, bishop b6, knight f5 e7, pawn d5 a6.
13 white and 9 black pieces are on the board; the puzzle position arises after move 27.
The position in numbers
Material is level — 30 points of pieces on each side (pawn = 1, knight and bishop = 3, rook = 5, queen = 9).
The white king stands on f1, the black king on h8.
It is White to move on move 27, with 42 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 7 pawns, Black 2. Files fully open (no pawns of either colour): c, g — 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
27. Rh7+ Kxh7 28. Ng5+ Kg8 29. h7#
Why it works
- Great move! rook to h7 keeps the pressure (#2).
- Well found: knight to g5 (#1).
- Precise: pawn to h7 is the top choice (#).
- The line ends in a forced mate in 3.
- If instead Kxh7, then Ng5+ and you stay on top.
Move by move
- 27. Rh7+ — rook to h7 with check
- Kxh7 — king to h7 (capture)
- 28. Ng5+ — knight to g5 with check
- Kg8 — king to g8
- 29. h7# — pawn to h7 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 #109.
SP-109 · 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 c1 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 d1 and g1; their long diagonals reach h5 and a7 once the e- and f-pawns step aside.
Every pawn on the second rank is defended from the very first move.
The setup belongs to the BastionGuard family; read right to left it becomes position 856.
The engine's main line opens with h3.
Morozov Balance Index: 94 of 100 — class A — most balanced. Engine evaluation of the starting position: +10 centipawns for White (depth 49, 400 000 000 nodes).
Explore position #109Provenance
Mined from the project's engine self-play games.
Pack 014 · SP-109
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