Winning blow: knight to b6 (d5·4)
c9-10766naming 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 1060 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 c1, queen h1, rook d1, bishop g2 a5, knight d5, pawn c2 h2 b3 f4 g4.
Black: king c8, queen d6, rook d7 g8, bishop b5 f8, knight a3, pawn a6 g6 b7 f7 h7.
11 white and 12 black pieces are on the board; the puzzle position arises after move 22.
The position in numbers
Black are ahead by 5 points of material (28 against 33; pawn = 1, knight and bishop = 3, rook = 5, queen = 9) — the tactic has to convert or outweigh that.
The white king stands on c1, the black king on c8.
It is White to move on move 22, with 36 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 5 pawns, Black 5. Files fully open (no pawns of either colour): d, e — natural highways for the rooks and queen. Half-open for White: a.
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
22. Nb6+ Qxb6 23. Bxb6 Bd6 24. Bxb7+
Why it works
- Great move! knight to b6 keeps the pressure (+4.4).
- Well found: bishop to b6 (+4.7).
- Precise: bishop to b7 is the top choice (+4.0).
- You win a piece — the queen.
- If instead Qxb6, then Bxb6 and you win the queen.
Move by move
- 22. Nb6+ — knight to b6 with check
- Qxb6 — queen to b6 (capture)
- 23. Bxb6 — bishop to b6 (capture)
- Bd6 — bishop to d6
- 24. Bxb7+ — bishop to b7 (capture) with check
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 attack
A piece steps aside and opens a second attack from the piece behind it.
A discovered attack works like a curtain: one piece steps off the line and unveils the long-range piece behind it. The beauty is that the moving piece can create a second threat of its own — two attacks in one move. Look for your stacked pairs: a bishop or rook behind a knight or pawn, aimed through them at something valuable. Send the front piece to the most aggressive square — a discovery without a second threat wastes half its power.
Remove the defender
Capture the guard first — then take what it protected.
Removing the defender is the straightforward plan: capture the guard first, then take what it guarded. Unlike deflection, the defender is not lured away — it is traded off or destroyed on the spot. Stare at the target you crave and ask who defends it, and whether that defender can be profitably eaten. Count the whole capture sequence, not just the first move — the trade must pay off at the end.
About this position
These pieces come from starting position #90.
SP-90 · ThroneScout — King on a central file (d/e) with a knight starting on the rim (a/h).
The king starts on d1, the rooks on c1 and g1, the queen on h1.
Castling long simply swaps the two pieces: the king on d1 and the rook on c1 trade places.
The bishops stand on e1 and f1; their long diagonals reach a5 and a6 once the d- and e-pawns step aside.
The second rank carries 2 pawns with no defender at all: a2, b2.
The setup belongs to the ThroneScout family; read right to left it becomes position 869.
The engine's main line opens with g4.
Morozov Balance Index: 34 of 100 — class C — noticeable edge. Engine evaluation of the starting position: +31 centipawns for White (depth 45, 400 000 000 nodes).
Explore position #90Provenance
Mined from the project's engine self-play games.
Pack 006 · SP-90
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