Mate in 3: knight to d7 (f6·2)
c9-15252naming 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.
Difficulty 1760 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.
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 f2, rook h1 e6, knight f6, pawn g2 h6.
Black: king f8, queen e3, bishop b4, pawn d4 g4 d5 e5 a7 h7.
7 white and 9 black pieces are on the board; the puzzle position arises after move 36.
The position in numbers
White are ahead by 6 points of material (24 against 18; 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 36, with 23 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 2 pawns, Black 6. Files fully open (no pawns of either colour): b, c, f — natural highways for the rooks and queen. Half-open for White: a, d, e.
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
36. Nd7+ Kg8 37. Re8+ Bf8 38. Rxf8#
Why it works
- Best move. knight to d7 is exactly what the engine plays (#2).
- Spot on — rook to e8 (#1).
- Precise: rook to f8 is the top choice (#).
- The line ends in a forced mate in 3.
- If instead Kg8, then Re8+ and you stay on top.
Move by move
- 36. Nd7+ — knight to d7 with check
- Kg8 — king to g8
- 37. Re8+ — rook to e8 with check
- Bf8 — bishop to f8
- 38. Rxf8# — rook to f8 (capture) and it is checkmate
Types in this puzzle
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.
Win the pinned piece
The pinned piece cannot run — attack it again and win it.
A pinned piece cannot flee, which means you can win it outright by attacking it one more time. Count attackers against defenders: if you outnumber them, the piece is yours. The best extra attacker is a pawn, since it costs less than anything it might capture. Do not rush the capture — build up the pressure first, then harvest.
Discovered attack
A piece steps aside and opens a second attack from the piece behind it.
A discovered attack works like a curtain: one piece steps off the line and unveils the long-range piece behind it. The beauty is that the moving piece can create a second threat of its own — two attacks in one move. Look for your stacked pairs: a bishop or rook behind a knight or pawn, aimed through them at something valuable. Send the front piece to the most aggressive square — a discovery without a second threat wastes half its power.
About this position
These pieces come from starting position #145.
SP-145 · RampartGuard — The king starts out on a wing file, b or g, with neither knight in a corner.
The king starts on g1, the rooks on c1 and h1, the queen on f1.
The king already stands on its castled square, so castling short moves only the rook, from h1 to f1.
A bishop starts in the corner on a1: it has a single diagonal, which the b-pawn unlocks, running out to h8.
One second-rank pawn starts with no defender at all: a2.
The setup belongs to the RampartGuard family; read right to left it becomes position 811.
The engine's main line opens with e3.
Morozov Balance Index: 94 of 100 — class A — most balanced. Engine evaluation of the starting position: +10 centipawns for White (depth 47, 400 000 000 nodes).
Explore position #145Provenance
Mined from the project's engine self-play games.
Pack 013 · SP-145
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