The solver is presented with 10 chess boards, each with a position that, although cannot be reached in a real game, is otherwise valid. Each position has an empty square with a circle. Given the piece bank at the top, solvers can infer that they must place one piece without replacement in each circle in order to produce the shortest forced checkmate. This is further confirmed by the fact that 5 of the boards are from White's perspective and 5 are from Black's perspective.

Each position is materially heavily stacked against the player, but can be solved by placing the correct piece in the circle. Some of the positions are ambiguous (for example, queens can always replace rooks or bishops), but there is only one permutation that results in checkmates on all 10 boards. The FENs disambiguate 2 of the positions, and they link to Lichess's board editor, both for convenience and additional cluing. However, intermediate chess players should be able to solve the positions without computer assistance, as most are classic mating patterns and the rest are intuitive.

The boards are ordered by the length of the mate. Reordering by the piece bank produces the final answer: **ROYAL VISIT**.

Board | Color | Piece | Pattern | Sequence | Length | A1Z26 |
---|---|---|---|---|---|---|

1 | B | Knight | En passant double check checkmate | 1... hxg3# | 1 | A |

2 | W | Queen | Smothered mate | 1. Nd7+ Ke8 2. Nxf6+ Kf8 3. Qe8+ Rxe8 4. Nd7+ Kg8 5. Qxb3+ Kh8 6. Nf7+ Kg8 7. Nxh6+ Kh8 8. Qg8+ Rxg8 9. Nf7# | 9 | I |

3 | W | Rook | Kill box | 1. Rxf8+ Ke7 2. Qf6+ Kd7 3. Rxd8+ Kc7 4. Qd6+ Kb7 5. Qxb8+ Kc6 6. Rd6+ Kc5 7. Qb6+ Kc4 8. Rxd4+ Kc3 9. Qb4# | 9 | I |

4 | W | Bishop | Windmill | 1. Rxg7+ Kh8 2. Rxf7+ Kg8 3. Rg7+ Kh8 4. Rxe7+ Kg8 5. Rg7+ Kh8 6. Rxd7+ Kg8 7. Rg7+ Kh8 8. Rxc7+ Kg8 9. Rg7+ Kh8 10. Rgxb7+ Kg8 11. Rg7+ Kh8 12. Rg1# | 12 | L |

5 | B | Pawn | N/A | 1... Qa8+ 2. Kg1 Qa7+ 3. Kh1 Qb7+ 4. Kg1 Qb6+ 5. Kh1 Qc6+ 6. Kg1 Qc5+ 7. Kh1 Qd5+ 8. Kg1 Qd4+ 9. Kh1 Qe4+ 10. Kg1 Qe3+ 11. Kh1 Qf3+ 12. Kg1 Qf2+ 13. Kh1 Qxh2+ 14. Rxh2 Qxh2+ 15. Qxh2 Qxh2# | 15 | O |

6 | W | Pawn | Damiano’s mate | 1. Rxa8+ Kxa8 2. Ra1+ Kb8 3. Ra8+ Kxa8 4. Ra1+ Kb8 5. Ra8+ Kxa8 6. Ra1+ Kb8 7. Ra8+ Kxa8 8. Ra1+ Kb8 9. Ra8+ Kxa8 10. Ra1+ Kb8 11. Ra8+ Kxa8 12. Ra1+ Kb8 13. Ra8+ Kxa8 14. Qa1+ Kb8 15. Qa7+ Kc8 16. Qa8+ Kd7 17. Qxb7+ Qc7 18. Qxc7# | 18 | R |

7 | B | Rook | Castling/Queen sacrifice | 1... Qxh5+ 2. Kg3 Qxh4+ 3. Kf3 Qxh3+ 4. Ke2 Qxf1+ 5. Kd2 Qxe1+ 6. Kc2 Qxd1+ 7. Kc3 Qxc1+ 8. Kb4 Qxa3+ 9. Kb5 Qxa4+ 10. Kb6 Rhb1+ 11. Qb2 Rxb2+ 12. Bb5 Qxa5+ 13. Kb7 Qxa7+ 14. Kc8 O-O+ 15. Rd8 Qa8+ 16. Qb8 Qxb8+ 17. Kxb8 Rxd8+ 18. Qc8 Ra8+ 19. Kxa8 Rxc8# | 19 | S |

8 | B | Queen | Back rank mate | 1... Qxa1+ 2. Rxa1 Rxa1+ 3. Rb1 Rxb1+ 4. Rxb1 Rxb1+ 5. Rxb1 Rxb1+ 6. Rc1 Rxc1+ 7. Rxc1 Rxc1+ 8. Rxc1 Rxc1+ 9. Rd1 Rxd1+ 10. Rxd1 Rxd1+ 11. Rxd1 Rxd1+ 12. Rxd1 Rxd1+ 13. Re1 Rxe1+ 14. Rxe1 Rxe1+ 15. Rxe1 Rxe1+ 16. Rxe1 Rxe1+ 17. Rf1 Rxf1+ 18. Rxf1 Rxf1+ 19. Rxf1 Rxf1+ 20. Rxf1 Rxf1# | 20 | T |

9 | B | Bishop | King chase | 1... Qa8+ 2. Kb6 Qa6+ 3. Kc5 Qc6+ 4. Kb4 Qc4+ 5. Ka3 Qa4+ 6. Kb2 Qa2+ 7. Kc1 Qb1+ 8. Kd2 Qd1+ 9. Ke3 Qd3+ 10. Kf4 Qe4+ 11. Kg5 Qg6+ 12. Kf4 Qg4+ 13. Ke3 Qe4+ 14. Kd2 Qd3+ 15. Kc1 Qd1+ 16. Kb2 Qb1+ 17. Ka3 Qa2+ 18. Kb4 Qa4+ 19. Kc5 Qc4+ 20. Kb6 Qc6+ 21. Ka7 Qa6+ 22. Kb8 Qa8# | 22 | V |

10 | W | Knight | Greek gift | 1. Qxh7+ Kxh7 2. Nfg5+ Kg8 3. Qh5 Ra1+ 4. Kc2 Rc1+ 5. Kxc1 Ra1+ 6. Kc2 Rc1+ 7. Kxc1 Ra1+ 8. Kc2 Rc1+ 9. Kxc1 Ra1+ 10. Kc2 Rc1+ 11. Kxc1 Ra1+ 12. Kc2 Rc1+ 13. Kxc1 Ra1+ 14. Kc2 Rc1+ 15. Kxc1 Ra1+ 16. Kc2 Rc1+ 17. Kxc1 Rfe8 18. Qxf7+ Kh8 19. Qh5+ Kg8 20. Qh7+ Kf8 21. Qh8+ Ng8 22. Nh7+ Kf7 23. Bh5+ g6 24. N3g5+ Ke7 25. Qg7# | 25 | Y |

Color | Piece | Length | A1Z26 |
---|---|---|---|

W | Pawn | 18 | R |

B | Pawn | 15 | O |

W | Knight | 25 | Y |

B | Knight | 1 | A |

W | Bishop | 12 | L |

B | Bishop | 22 | V |

W | Rook | 9 | I |

B | Rook | 19 | S |

W | Queen | 9 | I |

B | Queen | 20 | T |

### Authors' Notes

I've messed around with convoluted chess positions since I started playing chess, and I've wanted to write a chess puzzle since I started puzzlehunting. When I saw the answer, I knew it was meant to be—thematic to chess and a perfect title, and the letters were later in the alphabet, which would both challenge me and perhaps make Stockfish a little less useful.

The Damiano's mate, windmill, and back rank mate were easy to construct, so I kept them as buffers for the more constrained patterns. The smothered mate and king chase confirmed the puzzle's feasibility. After I ran out of patterns, I was inspired by IM Eric Rosen's Rosen trophies to generate the en passant double check checkmate, castling, and zigzag. The pattern with castling required more time to construct than the others combined, and I ultimately had to settle because I couldn't conceive a position where castling was the move that delivered checkmate.

Lichess study: https://lichess.org/study/RoDaOlJL

Uncurated cursed half-positions that I experimented with: https://lichess.org/study/ok8pOSKD