Chess puzzle (Checkmate)
Moves: 1. e4 c6 2. Nc3 d5 3. exd5 cxd5 4. Nf3 Bg4 5. d4 e6 6. Bb5+ Nc6 7. h3 Bxf3 8.
Qxf3 Nf6 9. Bg5 Be7 10. O-O O-O 11. Rfe1 Qb6 12. Bxc6 Qxc6 13. Nxd5 exd5 14.
Rxe7 Rfe8 15. Rxe8+ Rxe8 16. Bxf6 gxf6 17. c3 Qe6 18. a4 Kh8 19. a5 a6 20. Ra4
Qd6 21. Rb4 *
Position (FEN): 4r2k/1p3p1p/p2q1p2/P2p4/1R1P4/2P2Q1P/1P3PP1/6K1 b - - 3 21
Black to move.
Themes:  Endgame Mate in 1 
Puzzle rating: 1017
Best move: Re1#