Attack on the uncastled king: rook to f8 (f1·22)
c9-27036naming 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.
Mate in 3: a forced sequence that ends in checkmate.
Uncastled king: the enemy king is stuck in the centre — punish it before it castles.
Difficulty 1630 ShuffleRating — for advanced tacticians.
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.
In a mate in three every move must be forcing; the defender should never get a free tempo. Find the check or threat that herds the king, calculate the single defence to each, and confirm the net closes on the third move.
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.
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 d1, rook a1 f1, bishop c2 a3, knight d3 g5, pawn a2 d2 b3.
Black: king d8, rook h4 a8, bishop c7 c8, knight d4 d6, pawn b5 c6 a7 e7 h7.
10 white and 12 black pieces are on the board; the puzzle position arises after move 19.
The position in numbers
Black are ahead by 2 points of material (25 against 27; pawn = 1, knight and bishop = 3, rook = 5, queen = 9) — the tactic has to convert or outweigh that.
The white king stands on d1, the black king on d8.
It is White to move on move 19, with 36 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 3 pawns, Black 5. Files fully open (no pawns of either colour): f, g — natural highways for the rooks and queen. Half-open for White: c, e, h.
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
19. Rf8+ Ne8 20. Nf7+ Kd7 21. Nc5#
Why it works
- Great move! rook to f8 keeps the pressure (#2).
- Well found: knight to f7 (#1).
- Strong! knight to c5 is the sharp choice (#).
- The line ends in a forced mate in 3.
- If instead Ne8, then Nf7+ and you stay on top.
Move by move
- 19. Rf8+ — rook to f8 with check
- Ne8 — knight to e8
- 20. Nf7+ — knight to f7 with check
- Kd7 — king to d7
- 21. Nc5# — knight to c5 and it is checkmate
Types in this puzzle
Knight mate
The knight lands the killing blow from its unique angle.
In a knight mate the final blow comes from the knight — the only piece whose check can never be blocked. That makes it lethal against a cramped king: only a king move or capturing the knight itself can help. The sign: the squares around the king are occupied or covered, and there is a hop from which the knight checks while staying untouchable. Bring the knight over early — it is slower than the long-range pieces, but its strike cannot be parried.
Only move
Everything else loses — find the only move that holds.
An only move is a position where everything loses except one single continuation. You cannot play "by hand" here: run through fundamentally different defenses — run away, block, trade, counterattack — and discard the ones that fail. The hallmark of these puzzles is that the obvious moves lose quickly while the solution often looks strange. First understand exactly what the threat is — then the one saving move reveals itself.
Mate in 3
A forced checkmate in three moves.
Mate in three is a forced staircase: each of your moves narrows the opponent's choices, and the third one ends the game. Look for the start among checks and sacrifices — quiet first moves are rare in mating problems, but deliciously sneaky. Keep the tree in your head: every defense gets its own branch. Do not stop calculating after move two — see the final mating picture with your own eyes.
About this position
These pieces come from starting position #836.
SP-836 · ThroneScout — The king starts on d or e while at least one knight begins in a corner.
The king starts on d1, the rooks on a1 and f1, the queen on g1.
The kingside rook already stands on f1, so castling short moves only the king, from d1 to g1.
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 e2 is defended by the king alone — the same soft spot f2 is in the classical setup.
The setup belongs to the ThroneScout family; read right to left it becomes position 126.
The engine's main line opens with f4.
Morozov Balance Index: 59 of 100 — class B — balanced. Engine evaluation of the starting position: +24 centipawns for White (depth 48, 400 000 000 nodes).
Explore position #836Provenance
Mined from the project's engine self-play games.
Pack 012 · SP-836
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