Winning blow: knight to b5 (d6·5)
c9-21890naming 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 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.
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 a3, rook b1 d1, bishop a1 h1, knight d6, pawn a2 c2 f2 h3 b4 g4.
Black: king b8, queen e8, rook c8 d8, bishop f6 a8, knight g6 d7, pawn d4 b5 d5 e5 g5 b6 h7.
13 white and 15 black pieces are on the board; the puzzle position arises after move 17.
The position in numbers
Black are ahead by 4 points of material (34 against 38; 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 b8.
It is White to move on move 17, with 43 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 6 pawns, Black 7. No file is fully open, so the heavy pieces have to be pried in. Half-open for White: d, e.
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
17. Nxb5 Rc7 18. Qxa8+ Kxa8 19. Nxc7+ Kb8 20. Nxe8
Why it works
- Great move! knight to b5 keeps the pressure (+3.4).
- Well found: queen to a8 (+3.4).
- Strong! knight to c7 is the sharp choice (+3.3).
- Great move! knight to e8 keeps the pressure (+3.5).
- You win a piece — the queen.
- If instead Rc7, then Qxa8+ and you win the bishop.
Move by move
- 17. Nxb5 — knight to b5 (capture)
- Rc7 — rook to c7
- 18. Qxa8+ — queen to a8 (capture) with check
- Kxa8 — king to a8 (capture)
- 19. Nxc7+ — knight to c7 (capture) with check
- Kb8 — king to b8
- 20. Nxe8 — knight to e8 (capture)
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.
Deflection
Force the defender away from its duty — then strike what it guarded.
Deflection forces the guard to leave its post: a sacrifice or exchange drags it away from the piece or square it protects. First find the critical defender — the piece whose absence makes the mate or the material win possible. Then find the move it cannot ignore, which is usually a capture. Do not be stingy: if removing the guard wins the queen or mates, the sacrifice pays for itself many times over.
Decoy
A sacrifice lures the king or a piece onto a fatal square.
A decoy is the mirror image of deflection: you sacrifice to drag the king or a piece onto a fatal square. The classic is a queen or rook sac whose capture pulls the king into a knight fork, a discovered check or mate. Find the square where the target will be hit, then find the offer it cannot refuse. Calculate to the very end — a decoy only works when the follow-up is forced.
About this position
These pieces come from starting position #915.
SP-915 · BastionGuard — King shifted to c or f, knights kept clear of the edges — 168 positions in all.
The king starts on c1, the rooks on b1 and d1, the queen on e1.
The king already stands on c1, so castling long moves only the rook, from b1 to d1.
A bishop starts in the corner on a1: it has a single diagonal, which the b-pawn unlocks, running out to h8.
One second-rank pawn starts with no defender at all: a2.
The setup belongs to the BastionGuard family; read right to left it becomes position 35.
The engine's main line opens with e4, putting a pawn straight into the centre.
Morozov Balance Index: 55 of 100 — class B — balanced. Engine evaluation of the starting position: +25 centipawns for White (depth 44, 400 000 000 nodes).
Explore position #915Provenance
Mined from the project's engine self-play games.
Pack 008 · SP-915
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