Chess puzzle (Advantage)
Opening: Four_Knights_Game, Four_Knights_Game_Other_variations
Moves: 1. e4 e5 2. Nf3 Nc6 3. Nc3 Nf6 4. d3 Bc5 5. h3 O-O 6. Be2 h6 7. Be3 Bxe3 8.
fxe3 d6 9. a3 Nh5 10. Kf2 f5 11. g3 f4 12. exf4 exf4 13. g4 Ng3 14. Rg1 Ne5 15.
Nd5 c6 16. Nc3 Qb6+ 17. d4 Qxb2 *
Position (FEN): r1b2rk1/pp4p1/2pp3p/4n3/3PPpP1/P1N2NnP/1qP1BK2/R2Q2R1 w - - 0 18
White to move.
Themes:  Middlegame  
Puzzle rating: 1697
Best move: Na4