Bishop sacrifice in Kings Indian Defense

One of my colleagues recently won a game on chess.com with a nice bishop sacrifice. It appears that the mate was unstoppable after 12.Ng5. Has anyone got any ideas as to how Black should have played before the sacrifice?

IrishJon versus a-player .
1.d4 g6
2.e4 Bg7
3.c4 d6
4.Nf3 Nf6
5.Nc3 O-O
6.Bd3 Re8
7.h4 h5
8.Qc2 c6
9.e5 Ng4
10.Bxg6 fxg6
11.Qxg6 dxe5
12.Ng5 Rf8
13.Qh7#