Annotated Game #196: Your opponent is always dangerous

This third-round tournament game is a short morality play about greed, overconfidence and the benefits of never giving up if you aren't yet completely lost.  The main lesson for me is to calmly consolidate after my opponent blunders, and to always treat them as being dangerous.

[Event "?"] [Site "?"] [Date "????.??.??"] [Round "?"] [White "ChessAdmin"] [Black "Class C"] [Result "0-1"] [ECO "A25"] [Annotator "ChessAdmin/Komodo 11.2"] [PlyCount "40"] 1. c4 e5 2. Nc3 Nc6 3. g3 Nf6 4. Bg2 Be7 5. d3 O-O 6. a3 {an unusual but logical move in this position, as it takes away the b4 square from Black's knight and prepares b2-b4.} d6 {Black has a solid but unambitious setup.} 7. b4 a6 8. e3 {this isn't bad at all, and allows me to capitalize on Black's next blunder, but in general I'm making too many pawn moves in the opening. Without a Black threat of advancing the f-pawn, as occurs in some variations when Black plays an early ...f5, this is also unnecessary. Objectively, Nge2 followed by d4 or f4 is a decent plan.} (8. Nf3) 8... b5 $4 9. Bxc6 $18 Rb8 { my opponent, to her credit, fights on.} 10. cxb5 axb5 11. Bxb5 {here I start getting a bit greedy, figuring why not take the extra pawn? Again, it's objectively good with best play, but by moving the bishop off the h1-a8 diagonal it neglects my kingside, which is full of light-square holes.} Bb7 12. e4 {yet another pawn move.} (12. Nf3 $18) 12... c6 13. Ba4 d5 {by this point my opponent actually has the initiative and I should be very careful, given that my king is still in the center and I remain underdeveloped.} 14. Qc2 $6 ( 14. Nf3 {again is the best way to play, developing and getting my king closer to castling.}) 14... c5 15. Nge2 {Black by this point has at least partial compensation for the piece.} dxe4 {my opponent chooses to open lines in the center, which is a good practical way to play.} 16. dxe4 cxb4 17. axb4 Bxb4 18. O-O {despite my pieces not being at all coordinated or doing much of anything useful, this should now be enough to regroup and win rather easily.} Qc8 19. Ba3 Qh3 20. Bxb4 $4 {incredibly, I have a total thinking process fail and miss Black's next move. Greed is definitely a deadly sin.} (20. f3 {is necessary.}) 20... Ng4 $1 0-1