mmm, rather interesting move, white immediately opens the c file for use and creates possibilities of a minority attack against blacks queen side pawn majority, after ...exd5 black has half open e file for use with a rook.
4... exd5 5. Bc1g5
quite an aggressive move, pin can be broken with e7, or black can solidify his position with ...c6
5... Bf8e7 6. e3 h6 7. Bg5h4 Nb8d7
i dont like this move ...Nbd7 for although its not essentially weakening it serves no real purpose on d7 and more importantly it blocks the queens bishops diagonal, which would have found an excellent post on f5, occupying the weakened light squares and contesting the b1 - h7 diagonal slav style, anticipating the bishops move to d3, where it could exchange itself of for one of whites most dangerous attackers
8. Bf1d3
a beautiful post for the Kings Bishop, here it radiates power all over the chess board like some magnificent star.
8... a6
a waste of time, not sure what this move accomplishes, was Nb5 really a threat?
9. Qd1c2
Qc2 an interesting move, queen coordinates well with the bishop, although if Black opens the c file it may become vulnerable, Nf3 was also possible
9... c5
wow, an attempt by black to open the position, threatens to isolate his own queen pawn, while the move is certainly dynamic, his king remains in the centre
10. Ng1f3
developing a piece and defending the d pawn,
10... c4
this is an interesting move, it seeks to block the c file and challenge whites beautifully placed bishop and emphasises blacks queenside pawn majority
11. Bd3f5
bishops is forced to move, although white posts it to a very active square, Be2 may also have been possible, although it seems so passive there.