Victory in Twelve Moves

I recently won a game at chess.com in speed chess. My opponent was Qasaal of Somalia who played black. My opponent made a number of mistakes which allowed me to win quickly. Here are the moves of the game along with my commentary:

1. e4 e5
2. Nf3 Nc6
3. Bb5 a6
4. Bxc6 bxc6

Black makes a mistake. He should play dxc to open the c8-h3 diagonal for his bishop and d-file for his queen.

5. d4 Bb7
6. dxe Rb8

This move by black is not the best. It is better to develop the kingside bishop and knight to prepare for castling.

7. Nc3 c5

With this move black opens a diagonal for the queen bishop but the king knight and bishop are still on their original squares.

8. 0-0 Nh6
9. Bxh6 gxh6

I capture the knight to weaken black's kingside.

10. Nd5 c6

This is a mistake. My knight wants to go to f6. To stop this, black must play Bg7.

11. Nf6+ Ke7

Black's move is forced.

12. Qd6#

I achieve a quick and decisive victory because of black's lack of development, weakened pawn structure and inability to prevent moves such as Nf6+. Though material is almost even, black cannot protect his king. This in turn leads to his rapid downfall.