a game need analysis

I have a question about this game:

Is this move good? or what is fallacy in it?

20. b4

Thanks for comments.

i don't think 20.b4 is a good move.

20.b4 Qg3 21.Nd1 Ree6 and 22...Ref6,black has a good position.

A good game!

But I think 19.Nd3 is good!

thanks for the comment,it is nice!

You are welcome!

As it happens both of you had winning chances at one stage or other. Black missed a tactical chance 21-....Rgxe3  22-Rxe3  Qf4 wins important central pawn. I can not understand why you left pawn at e3. If you push it to e4 you get rid off your weaknesses and activate your heavy pieces. You can do  this on say 23-e4 as it discovers attack on g5. He can win a2 but all your pieces are active. After 23-e4 Bxa2  24-Rf4 white's game look much promising but you have to play very energetically if you wish to win. 

thanks ouachita's analysis of opening,and arunchess's analysis of middle game.

and my engine shows that 23.Rf4 Qg3+ 24.Kh1 Ba2 25.e4 Rh5 26.Re3 Qg5 27.Qf2+/-

it is similar to arunchess's analysis.

Anyway,thanks for analysis!

I think it's a perfect game besides 19.Kh1.

Why?

thanks,it is a good thought!