Winning blow: rook to c8 (c1·19)
c9-13061naming 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 1700 ShuffleRating — for advanced tacticians.
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 c1, bishop b1 f2, knight d2 d3, pawn b2 g2 a3 e3 f3 h3.
Black: king g8, rook h8, bishop f7 b8, knight d5 e6, pawn h4 f6 a7 b7 d7 e7 g7.
12 white and 13 black pieces are on the board; the puzzle position arises after move 18.
The position in numbers
Black are ahead by 1 points of material (23 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 g8.
It is White to move on move 18, with 37 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 6 pawns, Black 7. Files fully open (no pawns of either colour): c — natural highways for the rooks and queen. Half-open for White: 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
18. Rc8+ Kh7 19. Nf4+ g6 20. Rxh8+ Kxh8 21. Nxd5
Why it works
- Great move! rook to c8 keeps the pressure (+4.2).
- Spot on — knight to f4 (+4.3).
- Strong! rook to h8 is the sharp choice (+4.2).
- Great move! knight to d5 keeps the pressure (+4.4).
- You win a piece — the rook.
- If instead Kh7, then Nf4+ and you stay on top.
Move by move
- 18. Rc8+ — rook to c8 with check
- Kh7 — king to h7
- 19. Nf4+ — knight to f4 with check
- g6 — pawn to g6
- 20. Rxh8+ — rook to h8 (capture) with check
- Kxh8 — king to h8 (capture)
- 21. Nxd5 — knight to d5 (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.
About this position
These pieces come from starting position #236.
SP-236 · ThroneScout — The king starts on d or e while at least one knight begins in a corner.
The king starts on e1, the rooks on c1 and h1, the queen on d1.
Castling ends where it always does: king to g1 and rook to f1 on the short side, king to c1 and rook to d1 on the long one.
The bishops stand on b1 and g1; their long diagonals reach h7 and a7 once the c- and f-pawns step aside.
The second rank carries 2 pawns with no defender at all: b2, g2.
The setup belongs to the ThroneScout family; read right to left it becomes position 636.
The engine's main line opens with c4.
Morozov Balance Index: 16 of 100 — class D — largest edge. Engine evaluation of the starting position: +39 centipawns for White (depth 45, 400 000 000 nodes).
Explore position #236Provenance
Mined from the project's engine self-play games.
Pack 013 · SP-236
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