Chess puzzle (Checkmate)
Moves: 1. e4 c6 2. Nf3 d5 3. d3 dxe4 4. dxe4 Qxd1+ 5. Kxd1 Nd7 6. Nc3 e5 7. Be3 Ngf6
8. a4 Bb4 9. Bd3 Bxc3 10. bxc3 O-O 11. Ke2 Ng4 12. Bc5 Re8 13. Ba3 b6 14. c4
Nc5 15. Bb2 Nf6 16. Nxe5 Nfxe4 17. Bxe4 Nxe4 18. Kf3 Ng5+ 19. Kf4 f6 20. Nxc6
Re4+ 21. Kg3 *
Position (FEN): r1b3k1/p5pp/1pN2p2/6n1/P1P1r3/6K1/1BP2PPP/R6R b - - 2 21
Black to move.
Themes:  Middlegame Mate in 1 
Puzzle rating: 1025
Best move: Rg4#