Winning blow: pawn to g4 (g3·4)
c9-20504naming 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 1110 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.
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 b1, queen d3, rook a1 d1, bishop g2 c3, knight f3 a4, pawn b2 c2 f2 g3 h3 d4 a5.
Black: king a7, queen h7, rook d8 e8, bishop h5 f8, knight f5 c6, pawn d5 g5 a6 f6 h6 b7 c7.
15 white and 15 black pieces are on the board; the puzzle position arises after move 18.
The position in numbers
Material is level — 38 points of pieces on each side (pawn = 1, knight and bishop = 3, rook = 5, queen = 9).
The white king stands on b1, the black king on a7.
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 7 pawns, Black 7. Files fully open (no pawns of either colour): e — natural highways for the rooks and queen.
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
18. g4 Bg6 19. gxf5
Why it works
- Great move! pawn to g4 keeps the pressure (+2.1).
- Well found: pawn to f5 (+2.1).
- You win a piece — the knight.
- If instead Bg6, then gxf5 and you win the knight.
Move by move
- 18. g4 — pawn to g4
- Bg6 — bishop to g6
- 19. gxf5 — pawn to f5 (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.
Pawn fork
A humble pawn steps forward and attacks two pieces at once.
A pawn fork is a single pawn step that attacks two pieces at once. Since the pawn is the cheapest unit on the board, the trade is always a bargain — the opponent saves only one of the two targets. The pattern: two enemy pieces on the same rank, one file apart, with a square for your pawn between them. Before parking your pieces near enemy pawns, always ask whether one little push forks them both.
Quiet move
No check, no capture — yet this modest move decides the game.
A quiet move gives no check and takes nothing — yet it decides the game by creating an unstoppable threat or stealing the king's last square. This is the hardest class of moves: the eye hunts for loud blows while a modest shift does the winning. The clue: every forcing try runs into a defense, so seek the move that strengthens the threat or takes squares away. Train yourself to ask: what if I neither capture nor check, but quietly improve?
About this position
These pieces come from starting position #666.
SP-666 · BastionGuard — King off-centre on c or f with both knights on inner files.
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 e1 and f1; their long diagonals reach a5 and a6 once the d- and e-pawns step aside.
The pawn on b2, c2 is defended by the king alone — the same soft spot f2 is in the classical setup.
The setup belongs to the BastionGuard family; read right to left it becomes position 197.
The engine's main line opens with e4, putting a pawn straight into the centre.
Morozov Balance Index: 40 of 100 — class C — noticeable edge. Engine evaluation of the starting position: +29 centipawns for White (depth 42, 400 000 000 nodes).
Explore position #666Provenance
Mined from the project's engine self-play games.
Pack 007 · SP-666
Similar puzzles
In your browser or in the Android app. Nothing to install · Free, no ads