what is the best response for unusual g5 on step 8?

I probably wouldn't have wasted my last three moves and would have just taken 5 Nxe5 or 6 Nxe5.
The whole point is for you to take advantage of your opportunities instead of playing defensive chess for no reason.
If your opponent starts to make moves on the flanks, look to make moves in the center. So start preparing stuff like d4.

yeah, if you're playing vienna game a possible Nxe5 is a must know because in my cases it often happen
also for the g5 pawn storm, you can let him/her push his/her pawn and you can develop your piece and attack his/her king since his/her king isn't castled yet and center is a vulnerable place for king to be in. if your opponent is indicating queenside castling you should do pawn storm on the queenside to counter-attack
i think the Kh1 was to make a fxd3 in the future
Nope Kh1 was to remove annoying pin from dark squared bishop just in case queen comes on g file and lightsquare bishop captures at h3 if i had to push h3
yeah, if you're playing vienna game a possible Nxe5 is a must know because in my cases it often happen
also for the g5 pawn storm, you can let him/her push his/her pawn and you can develop your piece and attack his/her king since his/her king isn't castled yet and center is a vulnerable place for king to be in. if your opponent is indicating queenside castling you should do pawn storm on the queenside to counter-attack
Nxe5 was possible god how didn't i see it so dumb of me
I probably wouldn't have wasted my last three moves and would have just taken 5 Nxe5 or 6 Nxe5.
The whole point is for you to take advantage of your opportunities instead of playing defensive chess for no reason.
yes its stupid how defensive i play how Nxe5 was clearly a better option
If your opponent starts to make moves on the flanks, look to make moves in the center. So start preparing stuff like d4.
i will remember that
In chess, there is simply no substitute for alertness. You have to look at the board and notice possible checks, captures, and threats from move one! 5.Nxe5 (thanks, notmtwain) give you a virtually decisive advantage for nothing. Learning to look for moves like 5.Nxe5 is the most important single thing you can do to improve your chess. And 6.Nxe5 was your second chance to get a winning position before move 10
What was your plan with 8.Kh1? In any case, your 10.Ng1 looks fine. Black's 10...h5 weakens his dark squares and 11.Bg5! Would have made him pay.
Kh1 was to remove annoying pin from dark squared bishop just in case queen comes on g file and lightsquare bishop captures at h3 if i had to push h3 . Yeah right its stupid how defensive i play . Yes Nxe5 was best