Attack on the uncastled king: pawn to e5 (f4·90)
c9-21646naming 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.
Uncastled king: the enemy king is stuck in the centre — punish it before it castles.
Winning tactic: there is a move that gains a decisive advantage — find it.
Difficulty 920 ShuffleRating — for beginners taking their first steps in Chess960 tactics.
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.
An uncastled king in the centre is a standing target. Look for ways to open the central files and diagonals against it with checks and threats before it can shelter — every tempo the king spends in the middle is a chance for a combination.
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 g1, queen b4, rook a1 f1, bishop c2, pawn a2 d2 h2 b3 c3 g3 f4.
Black: king f8, queen f7, rook a8 h8, knight b6 e7, pawn e5 c6 a7 b7 g7 h7.
12 white and 12 black pieces are on the board; the puzzle position arises after move 17.
The position in numbers
Black are ahead by 2 points of material (29 against 31; pawn = 1, knight and bishop = 3, rook = 5, queen = 9) — the tactic has to convert or outweigh that.
The white king stands on g1, the black king on f8.
It is White to move on move 17, with 41 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 7 pawns, Black 6. No file is fully open, so the heavy pieces have to be pried in. Half-open for White: 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. fxe5 O-O 18. Rxf7
Why it works
- Great move! pawn to e5 keeps the pressure (+6.0).
- Spot on — rook to f7 (+5.9).
- You win a piece — the queen.
- If instead O-O, then Rxf7 and you win the queen.
Move by move
- 17. fxe5 — pawn to e5 (capture)
- O-O — king to h8
- 18. Rxf7 — rook to f7 (capture)
Types in this puzzle
Rook fork
The rook attacks two targets along rank and file at the same time.
A rook fork attacks two targets from one square — one along the file, the other along the rank. Look for enemy pieces standing at a right angle to each other, both visible from a single safe square. This is bread and butter in endgames, where a rook check picks up loose pieces and pawns along the way. Test every rook check you have: does it also hit something valuable on the other line?
Uncastled king
The king lingered in the middle — punish the delay.
Punishing the uncastled king: your opponent delayed castling, and now his king is stuck on its starting square under fire. In Chess960 this is deadlier than in classical chess — the king may start in the center or near the edge, and the familiar defensive setups simply do not apply. The signs: the victim still holds castling rights, and the files toward his king are half-open. Open lines before the king manages to hide.
Absolute pin
A piece is pinned against its king — it cannot legally move.
An absolute pin freezes a piece on the line between its own king and your long-range attacker: moving it is simply illegal. The pattern is three units on one straight line — your bishop, rook or queen, an enemy piece, and the enemy king behind it. A pinned piece neither attacks nor defends anything: treat it as if it were off the board. Pile up on it, ideally with a pawn, because running away is against the rules.
About this position
These pieces come from starting position #516.
SP-516 · BastionGuard — King off-centre on c or f with both knights on inner files.
The king starts on f1, the rooks on a1 and h1, the queen on e1.
Castling ends where it always does: king to g1 and rook to f1 on the short side, king to c1 and rook to d1 on the long one.
The bishops stand on b1 and c1; their long diagonals reach h7 and h6 once the c- and d-pawns step aside.
The pawn on g2 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 542.
The engine's main line opens with c4.
Morozov Balance Index: 69 of 100 — class B — balanced. Engine evaluation of the starting position: +21 centipawns for White (depth 45, 400 000 000 nodes).
Explore position #516Provenance
Mined from the project's engine self-play games.
Pack 005 · SP-516
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