Mate in 3: queen to b8 (b2·2)
c9-25318naming 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 1760 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 g2, queen b2, rook g1, bishop f3 d4, knight c5, pawn c3 d3 g3 e4 f4.
Black: king g8, rook h6, pawn h4 d5 g5 f7.
11 white and 6 black pieces are on the board; the puzzle position arises after move 25.
The position in numbers
White are ahead by 19 points of material (28 against 9; 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 g8.
It is White to move on move 25, with 50 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 5 pawns, Black 4. Files fully open (no pawns of either colour): a, b — natural highways for the rooks and queen. Half-open for White: h.
White hold the bishop pair, an edge in open lines. The White king has 5 empty squares to step to right now — the fewer they are, the closer a mating net.
Solution & explanation
Main line
25. Qb8+ Kh7 26. Qh8+ Kg6 27. Qg7#
Why it works
- Best move. queen to b8 is exactly what the engine plays (#2).
- Spot on — queen to h8 (#1).
- Precise: queen to g7 is the top choice (#).
- The line ends in a forced mate in 3.
- If instead Kh7, then Qh8+ and you stay on top.
Move by move
- 25. Qb8+ — queen to b8 with check
- Kh7 — king to h7
- 26. Qh8+ — queen to h8 with check
- Kg6 — king to g6
- 27. Qg7# — queen to g7 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 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.
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 #425.
SP-425 · RampartGuard — A wing king (b/g) with no knight on the a- or h-file.
The king starts on g1, the rooks on a1 and h1, the queen on c1.
The king already stands on its castled square, so castling short moves only the rook, from h1 to f1.
The bishops stand on d1 and e1; their long diagonals reach h5 and a5 once the e- 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 RampartGuard family; read right to left it becomes position 729.
The engine's main line opens with d4, putting a pawn straight into the centre.
Morozov Balance Index: 14 of 100 — class D — largest edge. Engine evaluation of the starting position: +40 centipawns for White (depth 44, 400 000 000 nodes).
Explore position #425Provenance
Mined from the project's engine self-play games.
Pack 013 · SP-425
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