Mate in 2: knight to d6 (f5·5)
c9-23925naming 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 2: the first move creates an unstoppable threat, the second delivers mate.
Difficulty 1220 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.
Mate in two usually opens with a forcing move — a check, a capture or an unstoppable threat — that strips the king of squares or defenders, so the follow-up mate becomes unavoidable. Look for the first move that leaves the opponent only losing replies.
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 e1, queen c5, rook a1 f1, bishop d1 d2, knight f5 c6, pawn a2 b2 e2 f2 h2 d3 c4 g4.
Black: king c8, queen h8, rook a8 f8, bishop g5 d7, knight g6, pawn e4 a7 f7 g7 h7.
16 white and 12 black pieces are on the board; the puzzle position arises after move 17.
The position in numbers
White are ahead by 6 points of material (39 against 33; pawn = 1, knight and bishop = 3, rook = 5, queen = 9) — the tactic has to convert or outweigh that.
The white king stands on e1, the black king on c8.
It is White to move on move 17, with 55 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 8 pawns, Black 5. No file is fully open, so the heavy pieces have to be pried in.
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
17. Nd6+ Kc7 18. Ba5#
Why it works
- Best move. knight to d6 is exactly what the engine plays (#1).
- Spot on — bishop to a5 (#).
- The line ends in a forced mate in 2.
- If instead Kc7, then Ba5# and it is mate.
Move by move
- 17. Nd6+ — knight to d6 with check
- Kc7 — king to c7
- 18. Ba5# — bishop to a5 and it is checkmate
Types in this puzzle
Mate in 2
A forced checkmate in two moves.
Mate in two: your move, any reply, then the mating blow. Start with the most forcing first moves — checks and sacrifices that shrink the opponent's options to almost nothing. Against every single reply you must have a mate ready, so check them all without exception. The common failure is analyzing the pretty defense and forgetting the boring one.
About this position
These pieces come from starting position #645.
SP-645 · ThroneScout — Centre-file king, rim knight: 204 of the 960 positions share this pattern.
The king starts on e1, 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 e1 to g1.
The bishops stand on c1 and d1; their long diagonals reach h6 and h5 once the d- and e-pawns step aside.
Every pawn on the second rank is defended from the very first move.
The setup belongs to the ThroneScout family; read right to left it becomes position 218.
The engine's main line opens with e4, putting a pawn straight into the centre.
Morozov Balance Index: 24 of 100 — class D — largest edge. Engine evaluation of the starting position: +35 centipawns for White (depth 45, 400 000 000 nodes).
Explore position #645Provenance
Mined from the project's engine self-play games.
Pack 008 · SP-645
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