Position after 19.Ng4! instead of 19.Rf3:
19.Ng4 threatens 20.Nh6+ Qxh6 21.Qxh6 with mate on g7 so ...
19. ... Qd6
And here white has 20.Bxg6!
This threatens mate on h7 and if 20. ... hxg6 21.Qh8 mate..
20. ... fxg6
This walks him into the f file so that white can bring the rook in on the attack with check.
21. ... Kf8
The bishop keeps e7 from the king AND brings the rook into action with forcing checks.
22. ... Kg7 (22. ... Qf4 just lasts a move longer.)
Note how the rook crashes through with check. This was set up by the preceding moves.
23. ... Kh8
Every move from Nh6 on was a forcing move with a direct threat. Black didn't have a second to breathe. Also note that every single white piece participated in the attack (even the queen prevented hxg6).
This is the way aggressive attacking chess SHOULD be played!!!