Mate in 2: rook to a8 (a5·3)
c9-14894naming 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 2: the first move creates an unstoppable threat, the second delivers mate.
Difficulty 1220 ShuffleRating — club-player level.
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.
Mate in two usually opens with a forcing move — a check, a capture or an unstoppable threat — that strips the king of squares or defenders, so the follow-up mate becomes unavoidable. Look for the first move that leaves the opponent only losing replies.
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 b5, rook h1 a5, knight d3 e4, pawn a2 b2 d2 c3 g4.
Black: king c8, queen g8, rook c6, bishop f4, knight e7 d8, pawn a4 d7.
11 white and 8 black pieces are on the board; the puzzle position arises after move 27.
The position in numbers
White are ahead by 5 points of material (30 against 25; 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 c8.
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 5 pawns, Black 2. Files fully open (no pawns of either colour): e, f, h — natural highways for the rooks and queen.
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. Ra8+ Kc7 28. Qb8#
Why it works
- Great move! rook to a8 keeps the pressure (#1).
- Spot on — queen to b8 (#).
- The line ends in a forced mate in 2.
- If instead Kc7, then Qb8# and it is mate.
Move by move
- 27. Ra8+ — rook to a8 with check
- Kc7 — king to c7
- 28. Qb8# — queen to b8 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 2
A forced checkmate in two moves.
Mate in two: your move, any reply, then the mating blow. Start with the most forcing first moves — checks and sacrifices that shrink the opponent's options to almost nothing. Against every single reply you must have a mate ready, so check them all without exception. The common failure is analyzing the pretty defense and forgetting the boring one.
Relative pin
A piece shields a more valuable one behind it — moving it loses material.
In a relative pin the piece shields not its king but something valuable behind it, usually the queen. Moving is legal but costly, because the piece behind falls. Look for three units on one line: your long-range piece, a cheaper enemy piece, and an expensive one hiding behind. Beware the classic trap — a relatively pinned piece can still move with check or a bigger threat, so verify before you cash in.
About this position
These pieces come from starting position #764.
SP-764 · BastionGuard — A c- or f-file king and two knights on inner files (b–g).
The king starts on c1, the rooks on a1 and f1, the queen on h1.
The king already stands on c1, so castling long moves only the rook, from a1 to d1.
The bishops stand on b1 and g1; their long diagonals reach h7 and a7 once the c- and f-pawns step aside.
One second-rank pawn starts with no defender at all: e2.
The setup belongs to the BastionGuard family; read right to left it becomes position 396.
The engine's main line opens with e4, putting a pawn straight into the centre.
Morozov Balance Index: 31 of 100 — class C — noticeable edge. Engine evaluation of the starting position: +32 centipawns for White (depth 48, 400 000 000 nodes).
Explore position #764Provenance
Mined from the project's engine self-play games.
Pack 008 · SP-764
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