The Bf3 is the most important piece, and, given the weakening of the central light squares, is fully worth a rook.

Of course, Black could get excellent counterplay with 12...Bb7 or 12...Nc6, but the move played in the game is stronger.

White should not open lines, but, on the contrary, try to keep the game as closed as possible. Therefore, 16.f5 was essential, although Black’s initiative is very strong all the same.

The white king has lost its only place of refuge, and now Black quietly brings up the rest of his pieces, to prepare the decisive blow.

And Black won.

Usually in such structures, Black puts his bishop on a4, and if possible supports it by ...b7-b5, cementing the queenside. This is exactly what Black would have done here if White had dawdled.

At the cost of a pawn, White activates his bishop, and it goes from being the most passive of his pieces to the most active.

White quietly increases the pressure, whilst Black cannot coordinate his pieces.

There is now a threat of Bg4-h3, followed by Qd1-g4 and Rf2xf7. He also threatens the immediate Bg4xe6, and then Qd1-g4.

Black resigned, since after 26...fxe6, there follows Qd1-g4.