Winning blow: bishop to a7 (f2·3)
c9-27636naming 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 b2, queen a8, rook f1, bishop h1 f2, knight c3, pawn c2 d2 h2 b3 e5.
Black: king c8, queen d7, rook b4, bishop d3 h8, knight e7 b8, pawn g5 d6 e6 h6 b7 c7.
11 white and 13 black pieces are on the board; the puzzle position arises after move 19.
The position in numbers
Black are ahead by 4 points of material (28 against 32; pawn = 1, knight and bishop = 3, rook = 5, queen = 9) — the tactic has to convert or outweigh that.
The white king stands on b2, the black king on c8.
It is White to move on move 19, with 47 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 5 pawns, Black 6. Files fully open (no pawns of either colour): a, f — natural highways for the rooks and queen. Half-open for White: g.
The White king has 5 empty squares to step to right now — the fewer they are, the closer a mating net.
Solution & explanation
Main line
19. Ba7 Qe8 20. Rf8 Qxf8 21. Qxb8+ Kd7 22. Qxf8
Why it works
- Great move! bishop to a7 keeps the pressure (+4.5).
- Well found: rook to f8 (+4.8).
- Strong! queen to b8 is the sharp choice (+4.8).
- Great move! queen to f8 keeps the pressure (+4.6).
- You win a piece — the queen.
- If instead Qe8, then Rf8 and you stay on top.
Move by move
- 19. Ba7 — bishop to a7
- Qe8 — queen to e8
- 20. Rf8 — rook to f8
- Qxf8 — queen to f8 (capture)
- 21. Qxb8+ — queen to b8 (capture) with check
- Kd7 — king to d7
- 22. Qxf8 — queen to f8 (capture)
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.
Win the pinned piece
The pinned piece cannot run — attack it again and win it.
A pinned piece cannot flee, which means you can win it outright by attacking it one more time. Count attackers against defenders: if you outnumber them, the piece is yours. The best extra attacker is a pawn, since it costs less than anything it might capture. Do not rush the capture — build up the pressure first, then harvest.
Skewer
A line attack forces the valuable piece to move, exposing the one behind it.
A skewer is a pin turned inside out: the valuable piece stands in front and something cheaper hides behind it. The big piece must step aside, and you collect the one that was sheltering in its shadow. Scan for the enemy king or queen sharing a file, rank or diagonal with another enemy piece. The deadliest version comes with check — the king moves, the rook behind it dies.
About this position
These pieces come from starting position #635.
SP-635 · BastionGuard — Off-centre king (c/f), no knight on the a- or h-file.
The king starts on c1, the rooks on a1 and f1, the queen on d1.
The king already stands on c1, so castling long moves only the rook, from a1 to d1.
A bishop starts in the corner on h1: it has a single diagonal, which the g-pawn unlocks, running out to a8.
One second-rank pawn starts with no defender at all: h2.
The setup belongs to the BastionGuard family; read right to left it becomes position 225.
The engine's main line opens with g4.
Morozov Balance Index: 69 of 100 — class B — balanced. Engine evaluation of the starting position: +21 centipawns for White (depth 43, 400 000 000 nodes).
Explore position #635Provenance
Mined from the project's engine self-play games.
Pack 010 · SP-635
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