Winning blow: pawn to b6 (a5·8)
c9-25640naming 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.
A fork made possible by the Chess960 piece placement.
Winning tactic: there is a move that gains a decisive advantage — find it.
Difficulty 1200 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.
A set-up fork needs one preparing move before the fork lands — a check that drives the king onto the forking square, or a capture that lines the targets up. Find the preparation first, then the fork it makes possible.
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 b1, queen e2, rook c1 g3, bishop h1 f2, knight c5, pawn b2 c2 d4 e4 a5.
Black: king c7, queen f6, rook d6 a7, bishop e8 h8, knight c6 e7, pawn h2 d5 e5 a6 b6 h7.
12 white and 14 black pieces are on the board; the puzzle position arises after move 27.
The position in numbers
Black are ahead by 4 points of material (33 against 37; pawn = 1, knight and bishop = 3, rook = 5, queen = 9) — the tactic has to convert or outweigh that.
The white king stands on b1, the black king on c7.
It is White to move on move 27, with 51 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 5 pawns, Black 6. Files fully open (no pawns of either colour): f, g — natural highways for the rooks and queen. Half-open for White: 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
27. axb6+ Kxb6 28. dxe5 Qxe5 29. Nd3+ d4 30. Nxe5
Why it works
- Great move! pawn to b6 keeps the pressure (+4.3).
- Well found: pawn to e5 (+4.4).
- Precise: knight to d3 is the top choice (+3.4).
- Best move. knight to e5 is exactly what the engine plays (+3.5).
- You win a piece — the queen.
- If instead Kxb6, then dxe5 and you stay on top.
Move by move
- 27. axb6+ — pawn to b6 (capture) with check
- Kxb6 — king to b6 (capture)
- 28. dxe5 — pawn to e5 (capture)
- Qxe5 — queen to e5 (capture)
- 29. Nd3+ — knight to d3 with check
- d4 — pawn to d4
- 30. Nxe5 — knight to e5 (capture)
Types in this puzzle
Setup fork
The random setup allows a fork that classical chess never sees.
A setup fork is a double attack that exists only because of the unusual starting squares — in classical chess these targets never stand side by side. Look for pairs of undefended pieces on your opponent's back rank and for squares from which a knight or pawn hits both at once. Such forks usually appear within the first moves, before the pieces disperse. In every new position, note right away which starting pieces are defended by no one.
Discovered check
The moving piece opens a check — and is free to grab anything meanwhile.
With a discovered check the moving piece unmasks a check from the piece standing behind it. While the king deals with the check, the piece that moved grabs whatever it likes, free of charge. Look for your long-range piece on a line with the enemy king, with exactly one of your own pieces in between. The rule: among all the ways to step aside, pick the one that captures or attacks the most expensive loot.
Winning exchange
A forced series of captures on one square ends in your favour.
A winning exchange is a forced series of captures on one square that leaves you ahead in material. It is pure arithmetic: count the attackers and defenders of the square and note the value of every piece in the queue. Capture in the right order — cheap pieces first, expensive ones later — or a winning trade turns into a losing one. The classic error is stopping the count halfway and missing the opponent's final recapture.
About this position
These pieces come from starting position #955.
SP-955 · RampartGuard — The king starts out on a wing file, b or g, with neither knight in a corner.
The king starts on b1, the rooks on a1 and c1, the queen on g1.
From b1 the king makes the longest journey Chess960 allows when castling short: five squares to g1.
A bishop starts in the corner on h1: it has a single diagonal, which the g-pawn unlocks, running out to a8.
One second-rank pawn starts with no defender at all: e2.
The setup belongs to the RampartGuard family; read right to left it becomes position 1.
The engine's main line opens with a4.
Morozov Balance Index: 80 of 100 — class A — most balanced. Engine evaluation of the starting position: +17 centipawns for White (depth 46, 400 000 000 nodes).
Explore position #955Provenance
Mined from the project's engine self-play games.
Pack 008 · SP-955
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