Mate in 3: queen to b7 (f3·3)
c9-28300naming 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 h2, queen f3, rook b1 d8, bishop f2 e8, pawn a2 b2 g3 c5.
Black: king e7, queen e5, rook g5, pawn h3 b5 e6 f6 a7.
10 white and 8 black pieces are on the board; the puzzle position arises after move 27.
The position in numbers
White are ahead by 10 points of material (29 against 19; pawn = 1, knight and bishop = 3, rook = 5, queen = 9) — the tactic has to convert or outweigh that.
The white king stands on h2, the black king on e7.
It is White to move on move 27, with 54 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 4 pawns, Black 5. Files fully open (no pawns of either colour): d — natural highways for the rooks and queen. Half-open for White: e, f, h.
White hold the bishop pair, an edge in open lines. 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. Qb7+ Qc7 28. Qxc7+ Kf8 29. Bxb5#
Why it works
- Best move. queen to b7 is exactly what the engine plays (#2).
- Spot on — queen to c7 (#1).
- Precise: bishop to b5 is the top choice (#).
- The line ends in a forced mate in 3.
- If instead Qc7, then Qxc7+ and you win the queen.
Move by move
- 27. Qb7+ — queen to b7 with check
- Qc7 — queen to c7
- 28. Qxc7+ — queen to c7 (capture) with check
- Kf8 — king to f8
- 29. Bxb5# — bishop to b5 (capture) and it is checkmate
Types in this puzzle
Discovered mate
A piece steps aside — and the one behind it delivers mate.
In a discovered mate the piece that moves is not the one that mates — the long-range piece behind it delivers the blow. The moving piece is completely free: it can land anywhere, ideally stealing the king's last squares or guarding key points. Look for your rook, bishop or queen lined up with the enemy king, with exactly one of your own pieces in between. When choosing the unveiling move, remember its second job — shutting the king's escape door.
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.
Counter-strike
Don't defend — answer the threat with a bigger one.
The counter-strike: instead of defending against the threat, you answer with a bigger threat of your own. While your opponent grabs a pawn, you deliver mate — the arithmetic favors you. Look for a counter when direct defenses fail: do you have a check, an attack on the queen, a mating threat? The beginner's error is meeting every threat with a reflexive defense without checking the counterattacking resources first.
About this position
These pieces come from starting position #124.
SP-124 · BastionScout — A knight on the a- or h-file, king on c or f — the mirror twin lands here as well.
The king starts on f1, the rooks on d1 and h1, the queen on c1.
The queenside rook already stands on d1, so castling long moves only the king, from f1 to c1.
The bishops stand on b1 and g1; their long diagonals reach h7 and a7 once the c- and f-pawns step aside.
The pawn on e2 is defended by the king alone — the same soft spot f2 is in the classical setup.
The setup belongs to the BastionScout family; read right to left it becomes position 844.
The engine's main line opens with d4, putting a pawn straight into the centre.
Morozov Balance Index: 75 of 100 — class A — most balanced. Engine evaluation of the starting position: +19 centipawns for White (depth 46, 400 000 000 nodes).
Explore position #124Provenance
Mined from the project's engine self-play games.
Pack 013 · SP-124
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