Mate in 3: rook to g8 (g1·3)
c9-24892naming 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 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.
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 b2, queen h5, rook g1, bishop d4 f7, knight d2, pawn a2 c2 h2 d3 f4.
Black: king c8, rook a8, bishop d7, knight b5, pawn f5 d6 a7 b7 c7 e7 h7.
11 white and 11 black pieces are on the board; the puzzle position arises after move 20.
The position in numbers
White are ahead by 10 points of material (28 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 b2, the black king on c8.
It is White to move on move 20, with 58 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 5 pawns, Black 7. Files fully open (no pawns of either colour): g — natural highways for the rooks and queen. Half-open for White: b, e.
White hold the bishop pair, an edge in open lines. The White king has 4 empty squares to step to right now — the fewer they are, the closer a mating net.
Solution & explanation
Main line
20. Rg8+ Be8 21. Be6+ Kb8 22. Qxe8#
Why it works
- Great move! rook to g8 keeps the pressure (#2).
- Spot on — bishop to e6 (#1).
- Precise: queen to e8 is the top choice (#).
- The line ends in a forced mate in 3.
- If instead Be8, then Be6+ and you stay on top.
Move by move
- 20. Rg8+ — rook to g8 with check
- Be8 — bishop to e8
- 21. Be6+ — bishop to e6 with check
- Kb8 — king to b8
- 22. Qxe8# — queen to e8 (capture) and it is checkmate
Types in this puzzle
Back-rank mate
The king is locked behind its own pawns — a heavy piece strikes the last rank.
The back-rank mate strikes a king locked behind its own unmoved pawns when a rook or queen crashes onto the last rank. The signs: no escape hole in front of the king, and the back rank guarded by a single piece or by nobody at all. Often that lone guard is deflected or traded off first, and only then comes the invasion. In your own games, make luft in time — one pawn move prevents a sudden catastrophe.
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 #535.
SP-535 · ThroneGuard — A central king (d or e) and two knights tucked onto inner files: the family that holds the standard array, SP-518.
The king starts on d1, the rooks on a1 and g1, the queen on e1.
Castling ends where it always does: king to g1 and rook to f1 on the short side, king to c1 and rook to d1 on the long one.
A bishop starts in the corner on h1: it has a single diagonal, which the g-pawn unlocks, running out to a8.
The pawn on c2 is defended by the king alone — the same soft spot f2 is in the classical setup.
The setup belongs to the ThroneGuard family; read right to left it becomes position 514.
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 #535Provenance
Mined from the project's engine self-play games.
Pack 012 · SP-535
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