Being too protective

The opponent being too protective can cost him the game itself. This was a very short game and ended very well for me. Here are the moves

I was playing black.

1.d3 e5

2.e3 d5

 This is how it all started. Normally white starts with d4. This provided me a chance to make a e5 move. In case white moves d4, e5 for black is a risky one.

3.Nd2 Nc6

4.Ne2 Nf6

Haven't seen anybody play Nd2 and Ne2, but this guy did.

5.b3 e4

6.Bb2 exd3

7.cxd3 Nb4

8.g3 Nxd3#

 He didn't realize even after I moved Nb4. This was suicidal.