Chess puzzle (Checkmate)
Moves: 1. d4 Nf6 2. c4 e6 3. Nc3 c5 4. Nf3 Nc6 5. e3 cxd4 6. Nxd4 g6 7. Be2 Bg7 8. O-O
O-O 9. b3 d5 10. cxd5 Nxd4 11. exd4 Nxd5 12. Nxd5 Qxd5 13. Bb2 Qg5 14. Qd3 Bd7
15. Rfd1 Bc6 16. Bf3 Bxf3 17. Qxf3 b6 18. Rac1 Rac8 19. Qb7 Rxc1 20. Rxc1 Bxd4
21. Bxd4 *
Position (FEN): 5rk1/pQ3p1p/1p2p1p1/6q1/3B4/1P6/P4PPP/2R3K1 b - - 0 21
Black to move.
Themes: Hanging Piece Endgame Back Rank Mate, Mate in 1 
Puzzle rating: 766
Best move: Qxc1#