Winning blow: knight to b5 (c7·2)
c9-25660naming 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 1390 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 e2, rook g1 c4, bishop a1, knight d3 c7, pawn d2 g2 h2 f3 a4 e4 a6.
Black: king f7, rook a7 b8, bishop d6, knight b3 g6, pawn d4 f4 e5 g5 h7.
13 white and 11 black pieces are on the board; the puzzle position arises after move 33.
The position in numbers
White are ahead by 2 points of material (26 against 24; pawn = 1, knight and bishop = 3, rook = 5, queen = 9) — the tactic has to convert or outweigh that.
The white king stands on e2, the black king on f7.
It is White to move on move 33, with 38 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 7 pawns, Black 5. Files fully open (no pawns of either colour): b, c — 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
33. Nb5 Rxa6 34. Rb1 Rxb5 35. axb5 Rxa1 36. Rxb3
Why it works
- Great move! knight to b5 keeps the pressure (+4.4).
- Well found: rook to b1 (+4.2).
- Strong! pawn to b5 is the sharp choice (+4.2).
- Best move. rook to b3 is exactly what the engine plays (+4.5).
- You reach a winning position (+4.5).
- If instead Rxa6, then Rb1 and you stay on top.
Move by move
- 33. Nb5 — knight to b5
- Rxa6 — rook to a6 (capture)
- 34. Rb1 — rook to b1
- Rxb5 — rook to b5 (capture)
- 35. axb5 — pawn to b5 (capture)
- Rxa1 — rook to a1 (capture)
- 36. Rxb3 — rook to b3 (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.
Overload
One defender guards two things — it cannot do both jobs.
Overloading exploits a defender with two jobs at once — guarding a piece and covering a mating square, for instance. It cannot do both: your first strike forces it to handle one duty and abandon the other. Find the overworked piece by asking what happens to each of its charges if it gets distracted. Then hit one target and collect the other — an overloaded defender only pretends to defend.
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 #768.
SP-768 · ThroneScout — King on a central file (d/e) with a knight starting on the rim (a/h).
The king starts on e1, the rooks on d1 and g1, the queen on c1.
The queenside rook already stands on d1, so castling long moves only the king, from e1 to c1.
A bishop starts in the corner on a1: it has a single diagonal, which the b-pawn unlocks, running out to h8.
The pawn on e2 is defended by the king alone — the same soft spot f2 is in the classical setup.
The setup belongs to the ThroneScout family; read right to left it becomes position 191.
The engine's main line opens with d4, putting a pawn straight into the centre.
Morozov Balance Index: 9 of 100 — class D — largest edge. Engine evaluation of the starting position: +44 centipawns for White (depth 47, 400 000 000 nodes).
Explore position #768Provenance
Mined from the project's engine self-play games.
Pack 010 · SP-768
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