Quite typical, really.

Not... quite so typical, though transpositions are possible into the main lines arising from 2.Nf3 followed by 3.d4. Here White leaves open the interesting possibilities of a Morra Gambit after 2...cxd4 3.c3!?

d4, you mean.

With this, White transposes into one of the major lines. But 3.d5 would have been quite a playable and good line.

This is a matter of opinion - personally, I think that this is quite reasonable - black is yet to hit back at the centre, and the knight on b8 is absent; the only piece that could have hit the queen. 5. ... Qa5+ is no worry.

In this instance: yes, by all means. There was no reason to allow Black to get away with the win of the pawn - if there were this would be a popular line for Black! 3...Nxd4 was most unusual. The alternative 3...cxd4 is much more common, and after 4.Nxd4 Black usually chooses one of these three moves: 4...Nf6 ('Main'); 4...e6 (Taimanov, possibly); 4...e5 (Lowenthal). Even 4...g6 is feasible. Note that having exchanged it off, Black can not attack the WQ with a knight at c6!

Premature.

Yes: and loses time rather than gaining any.

Agreed.

To be quite honest, I like 6. Bd2.

So do I. There was nothing wrong with the text move - it doesn't harm White's game. But by attacking Black's Q, 6.Bd2 would have gained time - a tempo - as Black would have had to do something again with his Queen. Then White could play 7.Nc3.

This forces the exchange, otherwise the rook goes.

This is a real nuisance for Black!

I only just realised that this gives away a rook, which I didn't see. So we both made blunders.

Well realised.

A successful distraction by Black. But look at 7...Qxd5 8.Nxd5 Rb8 9.Bf4 d6 10.0-0-0 and White has a lead in development.

You are learning. That is good that you noticed the opportunity. It may be true that you didn't see it then, but this kind of stuff helps you learn for your future games  

True enough, and 9. ... Qxc2 10. Bd3 wins for white.

The tactical situation justifies the second move by the knight before other pieces get moved.

The only move, as far as the eye could see, was 9. ... Qd8.

Either that or maybe 9...Qb8.

A second bite of the cherry.

Great moves to get to this point! Well executed.

This is winning.

This is not the reason - the reason was that he wanted to avoid mate. I am going to go into deep analysis: If he played 12. ... h6 or something, this would lead to 13. Qa5+ Ke8 13. Nc7+ Kd8 14. Ne6++ Ke8 15. Qd8# so I think this is why.

Yes, and if the pawn was still on e7, this would have led to mate.

13...Ke7 was not very well motivated: shutting in his K-Bishop, and his knight too if White were to play 14.e5. But, worse, it allowed this check, which will win a further piece.

Correct.

15.Bxd6ch was a little bit more efficient for White (by just one move), with mate in two: [a] 15...Kf6 16.Qe5#; [b] 15...Kd7 16.Qc7ch Ke8 17.Qxc8#

Not exactly, after Be8 you are a bit stuck. But mate is near.

It is not mate in 2, but mate in 3. Correct is 17. Qd4+! e5 18. Qxe5#

Well spotted.

Your annotation has been made into a puzzle, actually. Here it is: puzzle #137938.

I think you played well, Reuben. I am not saying that your opponent, harzer, played badly, but he was faced with a lot of unstoppable threats, such as the fork on c7, although you could have got the rook a long time ago. But, well played, both sides. @oodle3.

Black made it easy, but other than a single early slip, White took drastic advantage.

Yes, great job! You played this game very well Reuben! You figured out a good strategy which led you to the win! Excellent. Great efforts by both sides, and thank you for the annotation