Mate in 3: queen to a5 (c7·2)
c9-23419naming 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 c2, queen c7, rook c1, bishop b3 c3, pawn b2 d2 h2 e3 a4.
Black: king c5, queen a8, rook d6, knight d3, pawn e4 c6 a7 b7.
10 white and 8 black pieces are on the board; the puzzle position arises after move 28.
The position in numbers
White are ahead by 4 points of material (25 against 21; pawn = 1, knight and bishop = 3, rook = 5, queen = 9) — the tactic has to convert or outweigh that.
The white king stands on c2, the black king on c5.
It is White to move on move 28, with 38 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): f, g — natural highways for the rooks and queen. Half-open for White: c.
White hold the bishop pair, an edge in open lines. The White king has 2 empty squares to step to right now — the fewer they are, the closer a mating net.
Solution & explanation
Main line
28. Qa5+ b5 29. Kb1 Nxc1 30. Bb4#
Why it works
- Great move! queen to a5 keeps the pressure (#2).
- king to b1 develops smoothly.
- Strong! bishop to b4 is the sharp choice (#).
- The line ends in a forced mate in 3.
- If instead b5, then Kb1 and you stay on top.
Move by move
- 28. Qa5+ — queen to a5 with check
- b5 — pawn to b5
- 29. Kb1 — king to b1
- Nxc1 — knight to c1 (capture)
- 30. Bb4# — bishop to b4 and it is checkmate
Types in this puzzle
Boden's mate
Two bishops cross their diagonals over a king blocked by its own pieces.
Boden's mate crosses two bishop diagonals over a king blocked by its own pieces. The classic victim has castled on the queenside: its own rook and pawns have stolen the escape squares, and the bishops slash crosswise. The trigger is usually a queen sacrifice that blasts open the second diagonal. Whenever the enemy king is boxed in by its friends, ask whether both of your bishops can reach it on crossing diagonals.
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.
Absolute pin
A piece is pinned against its king — it cannot legally move.
An absolute pin freezes a piece on the line between its own king and your long-range attacker: moving it is simply illegal. The pattern is three units on one straight line — your bishop, rook or queen, an enemy piece, and the enemy king behind it. A pinned piece neither attacks nor defends anything: treat it as if it were off the board. Pile up on it, ideally with a pawn, because running away is against the rules.
About this position
These pieces come from starting position #302.
SP-302 · ThroneScout — The king starts on d or e while at least one knight begins in a corner.
The king starts on d1, the rooks on c1 and e1, the queen on a1.
Castling long simply swaps the two pieces: the king on d1 and the rook on c1 trade places.
The bishops stand on f1 and g1; their long diagonals reach a6 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 ThroneScout family; read right to left it becomes position 372.
The engine's main line opens with f3.
Morozov Balance Index: 83 of 100 — class A — most balanced. Engine evaluation of the starting position: +16 centipawns for White (depth 44, 400 000 000 nodes).
Explore position #302Provenance
Mined from the project's engine self-play games.
Pack 013 · SP-302
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