Beautiful Checkmate
My analysis of the game? Either you haven't inserted the game in to your post correctly... or the game hasn't started yet! 
Analysis:
Well, 13. b4 is, of course, a terrible blunder, which forces mate in 4.
Instead, White needed to regroup and pull the f3 knight back to g1, to develop it to d2. Even then, Black has a slight edge mostly due to his wonderful knight on f5.
After 13. Ng1 Bxg1 14. Kxg1 Qb6+ 15. Rf2 Black's position is preferable.
Thanks for posting.