Chess960 tactic on a8 (a1)
c9-12554naming 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: a forcing sequence that ends the game — the king has no escape.
Mate in 4: a forced checkmate in four moves — every reply is covered.
Difficulty 2120 ShuffleRating — expert level — few solve it at first try.
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.
This is a forced mating attack. Start from the enemy king: which of its squares are already covered, and which move takes away the rest while keeping the king in check? Forcing moves — checks and captures — are what turn an attack into mate.
A mate in four is a longer forced net: each of your moves is a check or an irresistible threat, and the king is driven step by step to a square where it is finally trapped. Verify that the defender has exactly one reply at every branch.
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 d2, queen b7, rook a1 f1, bishop g5, pawn c2 e2 c3 f4.
Black: king g8, queen f5, rook h7.
9 white and 3 black pieces are on the board; the puzzle position arises after move 39.
The position in numbers
White are ahead by 12 points of material (26 against 14; pawn = 1, knight and bishop = 3, rook = 5, queen = 9) — the tactic has to convert or outweigh that.
The white king stands on d2, the black king on g8.
It is White to move on move 39, with 54 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 4 pawns, Black 0. Files fully open (no pawns of either colour): a, b, d, g, h — natural highways for the rooks and queen.
The White king has 4 empty squares to step to right now — the fewer they are, the closer a mating net.
Solution & explanation
Main line
39. Ra8+ Qf8 40. Rxf8+ Kxf8 41. Qxh7 Ke8 42. Qe7#
Why it works
- Best move. rook to a8 is exactly what the engine plays (#3).
- Spot on — rook to f8 (#2).
- Precise: queen to h7 is the top choice (#1).
- Best move. queen to e7 is exactly what the engine plays (#).
- The line ends in a forced mate in 4.
- If instead Qf8, then Rxf8+ and you win the queen.
Move by move
- 39. Ra8+ — rook to a8 with check
- Qf8 — queen to f8
- 40. Rxf8+ — rook to f8 (capture) with check
- Kxf8 — king to f8 (capture)
- 41. Qxh7 — queen to h7 (capture)
- Ke8 — king to e8
- 42. Qe7# — queen to e7 and it is checkmate
Types in this puzzle
Ladder mate
Two heavy pieces climb line by line, cutting off every retreat.
The ladder mate uses two heavy pieces climbing rung by rung: one cuts the king off along a line, the other checks on the next line, driving him toward the edge. It is the classic two-rook technique — check, the king retreats one rank, the other rook checks, until mate on the last rank. The only danger is the king creeping close enough to attack one of your rooks. If it does, simply slide that rook to the far side of the same line.
Mate in 4+
A long forced mating combination.
Mate in four or longer is a marathon of forcing moves where the grip must never loosen. The tools are the same: checks, double threats and sacrifices that deny the opponent a single free tempo. Do not juggle the whole tree at once — walk the main line all the way to mate first, then verify the side branches. If somewhere the defender finds one quiet move that holds, your very first move was wrong.
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 #664.
SP-664 · ThroneGuard — A centre-file king with no knight on the edge; a position and its mirror twin always share this family.
The king starts on d1, the rooks on a1 and f1, the queen on h1.
The kingside rook already stands on f1, so castling short moves only the king, from d1 to g1.
The bishops stand on b1 and e1; their long diagonals reach h7 and a5 once the c- and d-pawns step aside.
One second-rank pawn starts with no defender at all: b2.
The setup belongs to the ThroneGuard family; read right to left it becomes position 205.
The engine's main line opens with c3.
Morozov Balance Index: 75 of 100 — class B — balanced. Engine evaluation of the starting position: +19 centipawns for White (depth 47, 400 000 000 nodes).
Explore position #664Provenance
Mined from the project's engine self-play games.
Pack 015 · SP-664
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