I was pleased with this game, a quick win… at the time. However, Nigel really didn’t like 12.g3. He said that while I brought my usual good calculation and energy to bear…. “very strong players use their back brains a lot”. He advised looking at a lot of QGA IQP positions.
I played 12.g3 so as to put my bishop on f4. I thought that if the pawns advance on the Q-side this would stop a rook coming to b8. I couldn’t see the point of playing it to g5. However, rather than seeing the clear reason for a move I think the point is to see the ugliness of g3 and in future not to entertain it as a possibility. You don’t want to block the third row for a possible rook lift. Nigel’s variation at move 12 makes a lot of sense to me now and is far more aesthetically pleasing.
The theme for Black of playing Nb4 to d5 was unknown to me then and apparently to Black, thankfully. It is an important theme in such positions.