Mate in 3: queen to a6 (e2)
c9-21928naming 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 e2, rook d1 g1, bishop g4, knight e4, pawn a2 f2 g2 b3 e5.
Black: king a3, queen h8, knight a8, pawn d5 c6 a7 f7 h7.
11 white and 8 black pieces are on the board; the puzzle position arises after move 31.
The position in numbers
White are ahead by 13 points of material (30 against 17; 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 a3.
It is White to move on move 31, with 40 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 5 pawns, Black 5. No file is fully open, so the heavy pieces have to be pried in. Half-open for White: c, d, h.
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
31. Qa6+ Kb2 32. Rd2+ Kc1 33. O-O#
Why it works
- Best move. queen to a6 is exactly what the engine plays (#2).
- Spot on — rook to d2 (#1).
- Precise: king to g1 is the top choice (#).
- The line ends in a forced mate in 3.
- If instead Kb2, then Rd2+ and you stay on top.
Move by move
- 31. Qa6+ — queen to a6 with check
- Kb2 — king to b2
- 32. Rd2+ — rook to d2 with check
- Kc1 — king to c1
- 33. O-O# — king to g1 and it is checkmate
Types in this puzzle
Castling mate
The rarest gem: castling itself delivers checkmate — a Chess960 speciality.
The castling mate is the rarest gem of all: the act of castling itself delivers checkmate. Chess960 makes it far more likely than classical chess — king and rook start on unusual squares, so castling can transform the attacking geometry in one move. The sign: the enemy king stands on the line where your rook will land, with the nearby squares already covered. Treat castling as a fighting move — the only move that moves two pieces at once.
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.
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.
About this position
These pieces come from starting position #185.
SP-185 · BastionScout — King shifted to c or f, with a knight committed to the corner from move one.
The king starts on f1, the rooks on b1 and g1, the queen on h1.
Castling short simply swaps the two pieces: the king on f1 and the rook on g1 trade places.
The bishops stand on d1 and e1; their long diagonals reach h5 and a5 once the e- and d-pawns step aside.
Every pawn on the second rank is defended from the very first move.
The setup belongs to the BastionScout family; read right to left it becomes position 777.
The engine's main line opens with g4.
Morozov Balance Index: 47 of 100 — class C — noticeable edge. Engine evaluation of the starting position: +27 centipawns for White (depth 45, 400 000 000 nodes).
Explore position #185Provenance
Mined from the project's engine self-play games.
Pack 012 · SP-185
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