Chess puzzle (Advantage)
Moves: 1. d4 Nf6 2. c4 c5 3. d5 b5 4. b3 g6 5. a4 b4 6. Nf3 a5 7. e3 Bg7 8. Bb2 d6 9.
h3 O-O 10. Bd3 Nbd7 11. O-O e5 12. dxe6 fxe6 13. Nbd2 Bb7 14. e4 Nb6 15. e5 Nh5
16. Ne4 d5 17. Nxc5 Qc8 18. Nxb7 Qxb7 19. cxd5 Nxd5 20. Ng5 Rae8 21. Nxh7 *
Position (FEN): 4rrk1/1q4bN/4p1p1/p2nP2n/Pp6/1P1B3P/1B3PP1/R2Q1RK1 b - - 0 21
Black to move.
Themes:  Middlegame  
Puzzle rating: 1944
Best move: Ndf4