Winning blow: rook to b8 (a8)
c9-25838naming 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 b1, rook a8, bishop g6, pawn g3 d4 h6 g7.
Black: king b4, rook e6, bishop a3, pawn b3 d5 e7.
7 white and 6 black pieces are on the board; the puzzle position arises after move 39.
The position in numbers
White are ahead by 1 points of material (12 against 11; 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 b4.
It is White to move on move 39, with 27 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 4 pawns, Black 3. Files fully open (no pawns of either colour): a, c, f — natural highways for the rooks and queen. Half-open for White: b, e.
The White king has 1 empty squares to step to right now — the fewer they are, the closer a mating net.
Solution & explanation
Main line
39. Rb8+ Kc4 40. Rxb3 Kxb3 41. Bc2+ Kc3 42. g8=Q
Why it works
- Great move! rook to b8 keeps the pressure (+4.7).
- Spot on — rook to b3 (+5.1).
- Strong! bishop to c2 is the sharp choice (+4.9).
- Great move! pawn to g8 keeps the pressure (+5.0).
- You win a piece — the pawn.
- If instead Kc4, then Rxb3 and you stay on top.
Move by move
- 39. Rb8+ — rook to b8 with check
- Kc4 — king to c4
- 40. Rxb3 — rook to b3 (capture)
- Kxb3 — king to b3 (capture)
- 41. Bc2+ — bishop to c2 with check
- Kc3 — king to c3
- 42. g8=Q — pawn to g8
Types in this puzzle
Sacrifice attack
Give up material to unleash a decisive attack.
A sacrificial attack gives up material on purpose to rip the king's shelter open and launch a decisive assault. The sac is sound when you get concrete assets in return: open lines to the king, tempi, pieces ready to pour in. The signs: a poorly sheltered king, your forces aimed at its home, defenders stranded far away. The iron rule is to calculate, not hope — once the material is gone, there is no way back.
Promotion race
Both sides push passers — win the race by a tempo.
A promotion race is a sprint between two passed pawns: both sides push toward the last rank, and victory goes to whoever queens first or queens with check. You will recognize it when both players have far-advanced passers that neither king can catch. Count the tempi literally, move by move, all the way to promotion. The classic mistake is spending a tempo on a "useful" move — in a race, almost any non-pawn move loses.
Mate defense
Mate is threatened — parry it and stay on top.
Mate defense: your opponent is one move from mating you — but it is your turn, and that changes everything. Find the defense that kills the mating threat while keeping your advantage: often a check or a counter-threat that leaves no time for the mate. First name the exact square where the mate would land — otherwise you are defending blind. The mistake is playing a "defensive" move that does not actually remove the threat.
About this position
These pieces come from starting position #956.
SP-956 · BastionGuard — A c- or f-file king and two knights on inner files (b–g).
The king starts on c1, the rooks on a1 and d1, the queen on h1.
The king already stands on c1, so castling long moves only the rook, from a1 to d1.
The bishops stand on b1 and g1; their long diagonals reach h7 and a7 once the c- and f-pawns step aside.
One second-rank pawn starts with no defender at all: e2.
The setup belongs to the BastionGuard family; read right to left it becomes position 12.
The engine's main line opens with a4.
Morozov Balance Index: 65 of 100 — class B — balanced. Engine evaluation of the starting position: +22 centipawns for White (depth 48, 400 000 000 nodes).
Explore position #956Provenance
Mined from the project's engine self-play games.
Pack 008 · SP-956
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