Winning blow: king to c1 (b1·20)
c9-09638naming 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.
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.
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, rook d1 e6, knight a3, pawn f3 c6.
Black: king b8, rook b2, bishop d4, knight f5, pawn b3 g6 g7.
6 white and 7 black pieces are on the board; the puzzle position arises after move 41.
The position in numbers
White are ahead by 1 points of material (15 against 14; 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 b8.
It is White to move on move 41, with 2 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 2 pawns, Black 3. Files fully open (no pawns of either colour): a, d, e, h — natural highways for the rooks and queen. Half-open for White: b, g.
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
41. Kc1 Rf2 42. Re8+ Kc7 43. Nb5+ Kxc6 44. Nxd4+
Why it works
- Great move! king to c1 keeps the pressure (+3.7).
- Well found: rook to e8 (+3.7).
- Strong! knight to b5 is the sharp choice (+3.8).
- Great move! knight to d4 keeps the pressure (+3.8).
- You reach a winning position (+3.8).
- If instead Rf2, then Re8+ and you stay on top.
Move by move
- 41. Kc1 — king to c1
- Rf2 — rook to f2
- 42. Re8+ — rook to e8 with check
- Kc7 — king to c7
- 43. Nb5+ — knight to b5 with check
- Kxc6 — king to c6 (capture)
- 44. Nxd4+ — knight to d4 (capture) with check
Types in this puzzle
Royal fork
A fork with check: the king must move, and the second piece is lost.
A royal fork is a fork with check — one of the two targets is the king itself. The check must be answered first, so nobody is left to rescue the second piece. Look for squares where your piece gives check and simultaneously attacks an undefended queen or rook. It is the most reliable fork of all, because your opponent literally has no choice.
Endgame tactic
Tactics live in the endgame too — strike while material is scarce.
Tactics do not retire when the queens come off: forks, pins and double attacks live on in the endgame. With so little material left, every tactical loss is almost always decisive. The signs are the usual ones — undefended pieces, king and piece on one line, a pawn about to promote. Even in a "technical" ending, scan for a shot before every move, both yours and your opponent's.
About this position
These pieces come from starting position #249.
SP-249 · BastionScout — Off-centre king plus a rim knight (a/h): 168 positions carry this shape.
The king starts on c1, the rooks on b1 and h1, the queen on f1.
The king already stands on c1, so castling long moves only the rook, from b1 to d1.
The bishops stand on d1 and e1; their long diagonals reach h5 and a5 once the e- and d-pawns step aside.
One second-rank pawn starts with no defender at all: a2.
The setup belongs to the BastionScout family; read right to left it becomes position 617.
The engine's main line opens with e4, putting a pawn straight into the centre.
Morozov Balance Index: 6 of 100 — class D — largest edge. Engine evaluation of the starting position: +48 centipawns for White (depth 45, 400 000 000 nodes).
Explore position #249Provenance
Mined from the project's engine self-play games.
Pack 010 · SP-249
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