Chess puzzle (Checkmate)
Opening: Queens_Gambit_Declined, Queens_Gambit_Declined_Other_variations
Moves: 1. d4 d5 2. c4 e6 3. Nf3 Nf6 4. g3 a6 5. a4 Nc6 6. Bg2 h6 7. O-O Bd7 8. Nc3
dxc4 9. e4 Ne7 10. e5 Nfd5 11. Nd2 c6 12. Nxc4 Nxc3 *
Position (FEN): r2qkb1r/1p1bnpp1/p1p1p2p/4P3/P1NP4/2n3P1/1P3PBP/R1BQ1RK1 w kq - 0 13
White to move.
Themes:  Middlegame Mate in 1, Smothered Mate 
Puzzle rating: 821
Best move: Nd6#