Mate in 3: knight to a5 (b3)
c9-27690naming 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 e1, queen g5, rook h1 d5, knight b3, pawn e2 h2 a3 f3 b4.
Black: king c6, bishop a7, pawn h4 b5 a6 e6 c7.
10 white and 7 black pieces are on the board; the puzzle position arises after move 31.
The position in numbers
White are ahead by 19 points of material (27 against 8; 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 c6.
It is White to move on move 31, with 46 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 5 pawns, Black 5. Files fully open (no pawns of either colour): d, g — natural highways for the rooks and queen. Half-open for White: c.
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
31. Na5+ Kb6 32. Qe3+ c5 33. Qxc5#
Why it works
- Best move. knight to a5 is exactly what the engine plays (#2).
- Spot on — queen to e3 (#1).
- Precise: queen to c5 is the top choice (#).
- The line ends in a forced mate in 3.
- If instead Kb6, then Qe3+ and you stay on top.
Move by move
- 31. Na5+ — knight to a5 with check
- Kb6 — king to b6
- 32. Qe3+ — queen to e3 with check
- c5 — pawn to c5
- 33. Qxc5# — queen to c5 (capture) and it is checkmate
Types in this puzzle
Supported queen mate
The queen delivers mate face to face, protected by a friend.
The supported queen mate is the most common pattern of all: the queen lands next to the king and mates because a friendly piece or pawn protects her. The king is helpless — capturing is impossible, and the queen covers every neighboring square herself. Hunt for a protected square beside the enemy king: a knight, bishop or pawn eyeing it turns her invasion into mate. Verify one thing — that the square really is defended, or the king eats her.
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.
Counter-strike
Don't defend — answer the threat with a bigger one.
The counter-strike: instead of defending against the threat, you answer with a bigger threat of your own. While your opponent grabs a pawn, you deliver mate — the arithmetic favors you. Look for a counter when direct defenses fail: do you have a check, an attack on the queen, a mating threat? The beginner's error is meeting every threat with a reflexive defense without checking the counterattacking resources first.
About this position
These pieces come from starting position #204.
SP-204 · ThroneGuard — King on a central file (d/e) with both knights on inner files — the classic-type setup.
The king starts on e1, the rooks on d1 and h1, the queen on a1.
The queenside rook already stands on d1, so castling long moves only the king, from e1 to c1.
The bishops stand on b1 and g1; their long diagonals reach h7 and a7 once the c- and f-pawns step aside.
One second-rank pawn starts with no defender at all: g2.
The setup belongs to the ThroneGuard family; read right to left it becomes position 668.
The engine's main line opens with c3.
Morozov Balance Index: 93 of 100 — class A — most balanced. Engine evaluation of the starting position: 0 centipawns for White (depth 45, 400 000 000 nodes).
In 50 self-play games White scored 46.0% (95% CI 33.0–59.6%).
Explore position #204Provenance
Mined from the project's engine self-play games.
Pack 013 · SP-204
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