Very wisely. The threat was 11...Nd4 12.Qd3 Nc2ch 13.Kd1 Nxa1.

I have a deja-vu...

Jkarp: you probably mean "...that WHITE left...". It's a good "principle": take advantage of the opponent's lack of developement as quick as possible, or he will catch up". Re8 was a nice preparation move, thoug.

His king is in the centre and as he has advanced pawns on both flanks, he can't really find safety there. So it is a reasonable idea to try and avoid the central files becomined opened. e3-e4 stops me from playing d4xe3 opening up the d file. So I gain a whole bishop, without losing anything.

f5 stunts to the mind at once. Who matters Qc5+, Kh8?, b5, Qb6!? (so if bxN, QxBb2...)

I think I would have preferred 12...Be6 and then ...f5.

Preventing f5 maybe?

White decided to play "non developemental chess"...  . But if Nh3, Nxh4. True is that, as black, I have thought it twice...  

14. Nh3 Nxh4 15. Ng5 and white may get counter-play down the h file.

I preferred 15...Nxb4 myself - and that was before I read your note! The threat is 16...Nc2ch, and it is not easy to meet. If 16.axb4 Bxb4ch 17.Nd2 ... (17.Kd1 Rac8 with a strong attack) 17...Qc2 18.Bc1 Bb5 and White is getting squashed.

Too late.

Bh3 would have been the natura answer.

Or, say, 16...Nxb4 17.axb4 Bxb4ch 18.Nd2 Qc2 19.Bc1 Nxd3ch 20.Qxd3 Ng3 21.Bxd2ch Bxd2 22.Qb3.

Qc8 was a very good move, despite "principles"...  

The position is screaming and yelling for ...Nxb4 to be played. It still looks very playable to me.

A lot of players get caught in situations like this. They stick to their plans even when the position calls for something else to be played. Sometimes, these alternative routes work, sometimes they don't. Goes to show that perspective is quite unique in chess and really depends on what each player sees on the board.

Shuts of the Queen's defence of d3.

If 19. Kd1, as you suggest, I take the bishop on b2 with check. Where does the king go? If it moves to c1 or c2 I have Nc6xb4 giving check to his king with my queen on c8 and if he then takes my knight on b2 then I have Qc2 mate.

When Black can afford to spurn a free and gratis bishop, you know the position is overwhelming. White has no defence in a thoroughly disorganised and dislocated position.

20...Rf3 I didn't see, but it looks pretty crushing! 20...Rf3 21.Qg1 N6xb4 22.axb4 Bb4ch 23.Nec3 ... (23.Kd1 Nxb2#) 23...dxc3ch 24.Bxc3 Bxc3ch 25.Nxc3 Rf2ch 26.Kxd3 Qd7ch 27.Nd5 Qb5ch 28.Ke3 Re2ch 29.Bxe2 Qe2#. White can stop the mate, but only at ruinous material cost.