Chess Miniature

I played  a game of speed chess at chess.com which ended on my twelfth move.  This qualifies it as a miniature.  My opponent was Pawnkiller of the USA who played black.  Here are the moves of the game along with my commentary:

1.  e4 c5
2.  d4 Nc6

Black's move is a surprise.  The reply dxc is very common.  Other possible replies are d5 and e6.  Black's reply allows me to put him on the defensive.

3.  d5 Nd4

Black makes a mistake.  The retreat Nb8 is much better.

4.  c3 Qa5

Black tries to save his knight by pinning my pawn.

5.  b4 cxb4

Now the black knight is undefended.

6.  Qxd4 bxc3

I centralize my queen.

7.  Nxc3 Nf6
8.  Bd3 g6
9.  Bd2 Bg7

Both sides prepare an attack against the enemy queen.

10.  Nb5 Qd8
11.  Rc1 Ng4

The problem with black's move is that the bishop is undefended.  Black needs to castle before making this move.

12.  Qxg7

Black resigns.  With my queen threatening black's rook and my knight ready to check on c7, black realizes the game is over.   Black commits a number of errors in this game.  The third move, Nd4, is a critical one which leads to the loss of his knight.