Mate in 3: queen to d4 (a1·2)
c9-28240naming 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 1630 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 f1, queen a1, rook h4, bishop g4, knight b5, pawn a2 h2 d5.
Black: king b6, rook b8 f8, bishop d4, pawn a4 b7 f7.
8 white and 7 black pieces are on the board; the puzzle position arises after move 28.
The position in numbers
White are ahead by 7 points of material (23 against 16; pawn = 1, knight and bishop = 3, rook = 5, queen = 9) — the tactic has to convert or outweigh that.
The white king stands on f1, the black king on b6.
It is White to move on move 28, with 33 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 3 pawns, Black 3. Files fully open (no pawns of either colour): c, e, g — natural highways for the rooks and queen. Half-open for White: b, f.
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
28. Qxd4+ Ka5 29. Qa7+ Kb4 30. Be2#
Why it works
- Best move. queen to d4 is exactly what the engine plays (#2).
- Spot on — queen to a7 (#1).
- Precise: bishop to e2 is the top choice (#).
- The line ends in a forced mate in 3.
- If instead Ka5, then Qa7+ and you win the bishop.
Move by move
- 28. Qxd4+ — queen to d4 (capture) with check
- Ka5 — king to a5
- 29. Qa7+ — queen to a7 with check
- Kb4 — king to b4
- 30. Be2# — bishop to e2 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.
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 #869.
SP-869 · ThroneScout — King in the middle of the rank, with a knight already committed to the corner.
The king starts on e1, the rooks on b1 and f1, the queen on a1.
The kingside rook already stands on f1, so castling short moves only the king, from e1 to g1.
The bishops stand on c1 and d1; their long diagonals reach h6 and h5 once the d- and e-pawns step aside.
The second rank carries 2 pawns with no defender at all: g2, h2.
The setup belongs to the ThroneScout family; read right to left it becomes position 90.
The engine's main line opens with Ng3, bringing the knight out to g3.
Morozov Balance Index: 61 of 100 — class B — balanced. Engine evaluation of the starting position: +23 centipawns for White (depth 46, 400 000 000 nodes).
Explore position #869Provenance
Mined from the project's engine self-play games.
Pack 012 · SP-869
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