Winning blow: rook to a7 (a8·5)
c9-10012naming 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 4: a forced checkmate in four moves — every reply is covered.
Winning tactic: there is a move that gains a decisive advantage — find it.
Difficulty 2350 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.
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.
This position hides a concrete tactic that wins material or mates. Start with the most forcing candidate moves — checks, captures and threats — and calculate each to a clear end before choosing; the winning line is usually the one the opponent cannot meet.
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 f3, rook a8, bishop b3, knight e5 c8, pawn a2 b2 f2.
Black: king b7, rook h2, knight f6, pawn g5.
8 white and 4 black pieces are on the board; the puzzle position arises after move 30.
The position in numbers
White are ahead by 8 points of material (17 against 9; pawn = 1, knight and bishop = 3, rook = 5, queen = 9) — the tactic has to convert or outweigh that.
The white king stands on f3, the black king on b7.
It is White to move on move 30, with 30 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 3 pawns, Black 1. Files fully open (no pawns of either colour): c, d, e, h — natural highways for the rooks and queen. Half-open for White: g.
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
30. Ra7+ Kxc8 31. Be6+ Kd8 32. Nc6+ Ke8 33. Ra8#
Why it works
- Great move! rook to a7 keeps the pressure (#3).
- Well found: bishop to e6 (#2).
- Precise: knight to c6 is the top choice (#1).
- Great move! rook to a8 keeps the pressure (#).
- The line ends in a forced mate in 4.
- If instead Kxc8, then Be6+ and you stay on top.
Move by move
- 30. Ra7+ — rook to a7 with check
- Kxc8 — king to c8 (capture)
- 31. Be6+ — bishop to e6 with check
- Kd8 — king to d8
- 32. Nc6+ — knight to c6 with check
- Ke8 — king to e8
- 33. Ra8# — rook to a8 and it is checkmate
Types in this puzzle
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.
Sacrifice attack
Give up material to unleash a decisive attack.
A sacrificial attack gives up material on purpose to rip the king's shelter open and launch a decisive assault. The sac is sound when you get concrete assets in return: open lines to the king, tempi, pieces ready to pour in. The signs: a poorly sheltered king, your forces aimed at its home, defenders stranded far away. The iron rule is to calculate, not hope — once the material is gone, there is no way back.
Decoy
A sacrifice lures the king or a piece onto a fatal square.
A decoy is the mirror image of deflection: you sacrifice to drag the king or a piece onto a fatal square. The classic is a queen or rook sac whose capture pulls the king into a knight fork, a discovered check or mate. Find the square where the target will be hit, then find the offer it cannot refuse. Calculate to the very end — a decoy only works when the follow-up is forced.
About this position
These pieces come from starting position #180.
SP-180 · BastionScout — King off-centre on c or f with a knight starting on the rim (a/h).
The king starts on f1, the rooks on d1 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 b1 and c1; their long diagonals reach h7 and h6 once the c- and d-pawns step aside.
The pawn on e2, f2 is defended by the king alone — the same soft spot f2 is in the classical setup.
The setup belongs to the BastionScout family; read right to left it becomes position 782.
The engine's main line opens with d4, putting a pawn straight into the centre.
Morozov Balance Index: 92 of 100 — class A — most balanced. Engine evaluation of the starting position: +12 centipawns for White (depth 47, 400 000 000 nodes).
Explore position #180Provenance
Mined from the project's engine self-play games.
Pack 015 · SP-180
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