Fournier recommends 8...Ne6 as a better try. But there is nothing wrong with 8...Ng4 provided that I had followed up after 9.Nxf8 with 9...Nxh2! (10.cxd4? Nf3+! 11.Qxf3 Qh4 wins) instead of my 9...Rxh2 10.g3 Qg5.
White missed 11.cxd4!, after which Black has two choices:
(a) 11...Nxf2!? 12.Qf3 Qxg3+ 13.Qxg3 fxg3 14.Rxf2 Rxf2 15.Ne6! Bxe6 16.Bxe6 Ke7 17.Bc4 exd4 18.Nd2 Rh8 19.Nf1 with clear advantage to White;
(b) 11...Rh6! 12.Qf3 Nh2 13.Qg2 Qh5 14.Nd2 Nxf1 15.Bxf1 Kxf8 16.dxe5 dxe5 17.b4 when White's advantage is small.