Winning blow: king to f1 (g2·4)
c9-14188naming 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 4: a forced checkmate in four moves — every reply is covered.
Winning tactic: there is a move that gains a decisive advantage — find it.
Difficulty 2120 ShuffleRating — expert level — few solve it at first try.
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.
A mate in four is a longer forced net: each of your moves is a check or an irresistible threat, and the king is driven step by step to a square where it is finally trapped. Verify that the defender has exactly one reply at every branch.
This position hides a concrete tactic that wins material or mates. Start with the most forcing candidate moves — checks, captures and threats — and calculate each to a clear end before choosing; the winning line is usually the one the opponent cannot meet.
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 g2, queen b8, rook a2, knight g5, pawn d3 h3 f4 d5.
Black: king g7, queen f1, pawn c5 g6 e7 f7.
8 white and 6 black pieces are on the board; the puzzle position arises after move 39.
The position in numbers
White are ahead by 8 points of material (21 against 13; pawn = 1, knight and bishop = 3, rook = 5, queen = 9) — the tactic has to convert or outweigh that.
The white king stands on g2, the black king on g7.
It is White to move on move 39, with 3 legal replies to weigh — only the line that keeps the advantage solves the puzzle. White are in check right now, so every reply must answer the check.
White keeps 4 pawns, Black 4. Files fully open (no pawns of either colour): a, b — natural highways for the rooks and queen. Half-open for White: c, e, g.
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
39. Kxf1 e6 40. Ra8 Kf6 41. Qh8+ Ke7 42. Qd8#
Why it works
- Great move! king to f1 keeps the pressure (#3).
- rook to a8 develops smoothly.
- Precise: queen to h8 is the top choice (#1).
- Best move. queen to d8 is exactly what the engine plays (#).
- The line ends in a forced mate in 4.
- If instead e6, then Ra8 and you win the queen.
Move by move
- 39. Kxf1 — king to f1 (capture)
- e6 — pawn to e6
- 40. Ra8 — rook to a8
- Kf6 — king to f6
- 41. Qh8+ — queen to h8 with check
- Ke7 — king to e7
- 42. Qd8# — queen to d8 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.
Mate in 4+
A long forced mating combination.
Mate in four or longer is a marathon of forcing moves where the grip must never loosen. The tools are the same: checks, double threats and sacrifices that deny the opponent a single free tempo. Do not juggle the whole tree at once — walk the main line all the way to mate first, then verify the side branches. If somewhere the defender finds one quiet move that holds, your very first move was wrong.
About this position
These pieces come from starting position #387.
SP-387 · BastionGuard — King shifted to c or f, knights kept clear of the edges — 168 positions in all.
The king starts on f1, the rooks on c1 and g1, the queen on b1.
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 a1: it has a single diagonal, which the b-pawn unlocks, running out to h8.
The second rank carries 2 pawns with no defender at all: d2, h2.
The setup belongs to the BastionGuard family; read right to left it becomes position 755.
The engine's main line opens with b4.
Morozov Balance Index: 83 of 100 — class A — most balanced. Engine evaluation of the starting position: +16 centipawns for White (depth 49, 400 000 000 nodes).
Explore position #387Provenance
Mined from the project's engine self-play games.
Pack 015 · SP-387
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