Nice, clean win

Any tips? Thanks.

Asthonishingly well played for your rating!

Thanks :) I also have been noticing some improvement lately 

but my rating is much higher over the board 

A very instructional game AB!

Thanks! Any tips on improvement?

Very well played, and it's nice you've annotated the game. I wish there were more annotated games around the forums to discuss because that would have been benefical for both those who played and those who looked at the games.

Do you think you got your opponent offguard by the opening? 5.b3?! is really strange as you note. Bf4 / Bg5 / g3 /even Nbd2 are possible.

I think 7...Bc3 may lead to interesting lines, as 8.Bxc3 dxc3 loses material for White (9.Nb1 Qxd1+ 10.Kxd1 c2+ double attack; then 11.Kd2 0-0-0+ and White's gone; 11.Kc1 cxb1=Q+ 12.Rxb1 Bxb1 13.Kxb1 0-0-0 and Black is winning), and otherwise 8.Qc1 (defending b2) leads to 8...Nb4 and again White loses material to the threat of ...Nc2. It looks like White has to sacrifice a minor piece or at least the exchange, for example 8.Rb1 Bxb1 9.Qxb1:

On move 10, I think ...0-0-0 is good because it gives you king safety and develops your queen's rook while keeping different options - either a kingside attack or a central push with the d pawn. With Bh3 / h4 White may delay or avoid kingside castling, while with 10...0-0-0 you can continue to yse your initiative.

White weakened his kingside and it was strange for him to castle under attack. You played the attack very well, White didn't have time to put up some defense. On move 21 Black really can't capture on f1 because of the Bg4 threat in response. You were right to continue building up the attack.

Nice game for you as a whole

Thanks, I was considering Bc3 but I definitely overestimated it.

Turns out white's best chance is sacrificing the exchange with a partially open king. Even though it's an equal position I think I have the better chances.

8. Qc1 Nb4 (white can't avoid the fork on c2)

9. Bxc3 (e4 isn't good) bxc3 10. Qxc3 Nc2+ 11. Kd1 Nxa1 12. Qxa1

Now I plan to play Qd7 but castle Kingside so I can safely try to rip open lines on the queenside. Plus, I plan to double up on the d file with my queen and f8 rook. Anyway I'm material equal so I'm fine there.

I think after 8.Qc1 Nb4 9.Bxc3 you have 9...Nc2+ as an interpolation, and then 10.Kd1 dxc3 11.Rb1 cxd2 12.Nxd2 Qd4 with even greater material gain, especially after ...0-0-0.

Wow my engine really sucks. Yeah, white has to give up his queen, then take the pawn on d4. White has two pieces and two pawns for the queen, black has a slight advantage. It's still a fight. Interesting imbalance though!