Chess puzzle (Checkmate)
Moves: 1. d4 Nf6 2. c4 e6 3. e3 Bb4+ 4. Nc3 Qe7 5. a3 Bxc3+ 6. bxc3 O-O 7. Nf3 d6 8.
Bd3 e5 9. Be2 Nc6 10. O-O Bf5 11. Nh4 Bd7 12. Nf3 Rae8 13. h3 Ne4 14. Qc2 f5
15. Rb1 b6 16. Nd2 exd4 17. Nxe4 d3 18. Qxd3 fxe4 19. Qd5+ Kh8 20. a4 Ne5 21.
Ra1 Nf3+ 22. Kh1 Bxh3 23. gxh3 Qh4 24. Kg2 Rf6 25. Rh1 Rg6+ 26. Kf1 Qxh3+ 27.
Rxh3 *
Position (FEN): 4r2k/p1p3pp/1p1p2r1/3Q4/P1P1p3/2P1Pn1R/4BP2/R1B2K2 b - - 0 27
Black to move.
Themes:  Middlegame Mate in 1 
Puzzle rating: 850
Best move: Rg1#