Mate in 2: knight to c6 (b4)
c9-22117naming 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 1320 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 d2, rook b3, bishop e4, knight f3 b4, pawn a2 e2 d3.
Black: king b8, queen g2, rook h8, knight c5 e8, pawn g6 c7 d7 f7 h7.
8 white and 10 black pieces are on the board; the puzzle position arises after move 20.
The position in numbers
Black are ahead by 8 points of material (17 against 25; pawn = 1, knight and bishop = 3, rook = 5, queen = 9) — the tactic has to convert or outweigh that.
The white king stands on d2, the black king on b8.
It is White to move on move 20, with 30 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): b — natural highways for the rooks and queen. Half-open for White: c, f, g, h.
The White king has 6 empty squares to step to right now — the fewer they are, the closer a mating net.
Solution & explanation
Main line
20. Nc6+ Ka8 21. Rb8#
Why it works
- Great move! knight to c6 keeps the pressure (#1).
- Well found: rook to b8 (#).
- The line ends in a forced mate in 2.
- If instead Ka8, then Rb8# and it is mate.
Move by move
- 20. Nc6+ — knight to c6 with check
- Ka8 — king to a8
- 21. Rb8# — rook to b8 and it is checkmate
Types in this puzzle
Arabian mate
Rook and knight — the oldest mate: the rook strikes next to the cornered king.
The Arabian mate is the oldest named pattern: the king is driven into the corner and the rook mates right next to it, guarded by a knight. The geometry is exact: king on h8, rook striking from h7, knight on f6 both protecting the rook and covering g8. The knight is irreplaceable — only it can guard the rook at point-blank range and hold the escape square at once. Look for the pattern when your knight is anchored two steps from the enemy corner.
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 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 #707.
SP-707 · BastionGuard — Off-centre king (c/f), no knight on the a- or h-file.
The king starts on c1, the rooks on b1 and g1, the queen on d1.
The king already stands on c1, so castling long moves only the rook, from b1 to d1.
A bishop starts in the corner on a1: it has a single diagonal, which the b-pawn unlocks, running out to h8.
The second rank carries 2 pawns with no defender at all: a2, f2.
The setup belongs to the BastionGuard family; read right to left it becomes position 435.
The engine's main line opens with b4.
Morozov Balance Index: 20 of 100 — class D — largest edge. Engine evaluation of the starting position: +37 centipawns for White (depth 44, 400 000 000 nodes).
Explore position #707Provenance
Mined from the project's engine self-play games.
Pack 010 · SP-707
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