The so-called "Hunt Variation" - white attempts to develop his pieces while gaining tempo by chasing black's knight around the board. The main drawback is that the advanced center pawns become targets.

Most common I've seen is 6.d4, where 6 ... d6 7.cxd6 cxd6 transposes to a Sicilian-like position, but I think instead that simply playing 6 ... b6 soon equalizes.

!? The sharpest continuation, and IMO black's best chance to gain advantage.

! 9.Qh5 g6 just helps black defend his position, for example 10.Qf3 g5, or 10.Qg4 h5, or 10.Qh3 g5 followed by 11 ... h5, etc.

not 10.Qxg5 Qxg5 11.Bxg5 Nxe5! where 12.Bf6 is met by 12 ... Bxf2+! 13.Ke2 (13.Kxf2 Ng4+ wins) Nxc4 14.Bxh8 Bxg1 followed by ... Nxb2 and black is winning, IMO

on 12. Bxe7 I was planning 12 ... Rxg4 13.Bxd8 Rxc4 followed by Nxe5, and black should have a good game

Black's plan is to fianchetto the light-squared bishop and O-O-O, then start operations on the white K using the half-open g-file & long diagonal.

? I think this B belongs on the a6-f1 diagonal, otherwise white has trouble contesting the f-file. Now black's new plan is to move ... Ba6 and use the f-file for himself. Better, IMO is 17.Qf3 which white has to play at some point anyway.

Controlling the important diagonal. Now black switches to "plan B"

? I'm not sure what this move accomplishes. Now c3 becomes a juicy target and gives black tactical tricks.