Chess960 tactic on b2
c9-13119Opens 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 a1, queen d3, rook a8, bishop c2, knight f3, pawn b3 e4 g4 h5.
Black: king h7, bishop b2, knight b5, pawn c6 d6 h6 b7.
9 white and 7 black pieces are on the board; the puzzle position arises after move 39.
The position in numbers
White are ahead by 14 points of material (24 against 10; pawn = 1, knight and bishop = 3, rook = 5, queen = 9) — the tactic has to convert or outweigh that.
The white king stands on a1, the black king on h7.
It is White to move on move 39, with 3 legal replies to weigh — only the line that keeps the advantage solves the puzzle. White are in check right now, so every reply must answer the check.
White keeps 4 pawns, Black 4. Files fully open (no pawns of either colour): a, f — natural highways for the rooks and queen. Half-open for White: c, d.
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
39. Kxb2 Kg7 40. e5 Kf7 41. Qg6+ Ke7 42. Qe8#
Why it works
- Best move. king to b2 is exactly what the engine plays (#3).
- pawn to e5 develops smoothly.
- Precise: queen to g6 is the top choice (#1).
- Best move. queen to e8 is exactly what the engine plays (#).
- The line ends in a forced mate in 4.
- If instead Kg7, then e5 and you win the bishop.
Move by move
- 39. Kxb2 — king to b2 (capture)
- Kg7 — king to g7
- 40. e5 — pawn to e5
- Kf7 — king to f7
- 41. Qg6+ — queen to g6 with check
- Ke7 — king to e7
- 42. Qe8# — queen to e8 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 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.
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 #72.
SP-72 · 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 h1, the queen on g1.
The queenside rook already stands on d1, so castling long moves only the king, from f1 to c1.
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 BastionScout family; read right to left it becomes position 893.
The engine's main line opens with d4, putting a pawn straight into the centre.
Morozov Balance Index: 20 of 100 — class D — largest edge. Engine evaluation of the starting position: +37 centipawns for White (depth 46, 400 000 000 nodes).
Explore position #72Provenance
Mined from the project's engine self-play games.
Pack 015 · SP-72
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