Chess puzzle (Checkmate)
Moves: 1. e4 c5 2. Nf3 g6 3. d4 cxd4 4. Nxd4 Nc6 5. Nc3 a6 6. Be3 Bg7 7. Qd2 Nf6 8.
Nxc6 bxc6 9. Bh6 O-O 10. O-O-O Rb8 11. Bxg7 Kxg7 12. f4 Qb6 13. b3 e6 14. e5
Nd5 15. Nxd5 cxd5 16. Bd3 a5 17. h4 a4 18. h5 axb3 19. axb3 Qa7 20. hxg6 *
Position (FEN): 1rb2r2/q2p1pkp/4p1P1/3pP3/5P2/1P1B4/2PQ2P1/2KR3R b - - 0 20
Black to move.
Themes:  Middlegame Mate in 1 
Puzzle rating: 819
Best move: Qa1#