A lesson in attack

A training game against one of my students. The student gives the teacher a lesson in attacking.

I am playing black against this young boy.

16. a5

A positional move from a young student. I had only expected him to defend the d-pawn.

16...Nxd4 ?!

Already a mistake according to the computer. 16... Nxe3 17. Qxe3 was better
for white according to him but I begged to differ. 

17. Bxa6 Bxa6 18. Bxd4 O-O 19. Bxg7 Kxg7 20. Qd4+ f6

20... e5! 21. fxe5 Bxf1 22. Ng4 c5 (22... Be2 23. e6+ f6 24. exd7 Bxg4?  25. Nxf6 Rxf6 26. axb6 surprisingly leaves black helpless. 23. Qe3 g5 24. Kxf1 Black stands better although this was
difficult to evaluate over the board. 

21. Rd1 Rf7 22. Nd6

This looked attractive although I was more worried of (22. axb6 Qxb6 23. Qxb6 Nxb6 24.
Rda1 Bb7 25. Rxa8 Bxa8 26. Ra6 Rb7 27. Nc5 Rb8 28. Ra7+ winning

 22... Re7 23. Ng4 Rf8 24. Rg3

Very unpleasant position for black after this.

24... Kh7 25. f5! exf5 26. Nxh6 !! f4

26... Kxh6 27. Nxf5+Kh7 28. Qh4+ Kg8 29. Rxg6+ Kf7 30. Rg7+ Ke8 31. Rxe7+ Kd8 32. Qh7 Bc8 33. Qg7 is also hopeless. 

27. Nhf5 fxg3

27... Re5 28. Qxf4 Rxf5 29. Qxf5 ! pointed out by white afterwards.

28.Qh4+ Kg8 29. Nxe7+ Kg7 30. Qxg3 Ne5 31. Ndf5+

31. Nxg6 would have ended it too.

31... Kf7 32. Nxg6 1-0