After 5...Nc6 the pawn is attacked 3 times and defended twice so you need to defend it c3 or Be3 (you can't really capture or it will stop you castling).

Black shouldn't capture the knight for central control, he should do it because it would put him a piece up! You let him off the hook when he gave you an opportunity to reconsider leaving it unprotected!

12. g4 I'm not sure serves a useful purpose and allows him to attack your kingside pawns easily and rip away the defence of your king. Which he did by adding a second attacker (the knight).

You're just not counting properly which pieces are attacking which pawns or pieces and move 17 just throws away a rook, but really you were already lost.

You didn't really have an option to use your king move with his rook on that rank. He could play Re2 and trap your king in 3 squares while eating your pawns with his king.

What  about  variations ?

This game is kinda interesting, because I think you start making mistakes on move 3, maybee even move 2 is debatable.  If your going to play e4 so early, play it your first move. I don't like your d4, Nc3, e4 line at all.  If your opponent had played something passive like 1....e6 or 1....d6 then I think the e4 move is fine, but I don't like the fact taht you are giving your opponent a half open d file so easily.  The half open d file can be very dangerous as it was in this game.  Playing e4 on move 3 allowed him to open the d file on his terms, instead of on your terms.

I think what you really should work on is not blundering, strategy lessons can come at a later time, when you don't blunder as often.  I'm not saying that you need to be blunder free before working on strategy because I blunder in just about every game I play, but not as often or as egregious as the blunders that you have.  Work on recognizing what pieces can be captured and how many times pieces are being attacked.  You will improve a lot if you just don't blunder as often.  I know it's difficult when you are a beginner, but with practice it will become easier.

The other move that I wanted to touch on was 12. g4, this is strategic concept that is important to learn on your first chess lesson.  Don't move the pawns infront of your king unless you have too.  Higher level players have very specific reasons for moving pawns infront of their king, such as playing h3, but at this point in your chess playing, it's best just to abide by the rule that unless you really have too, don't move those pawns infront of your king.  You will learn when it is appropriate later in your chess life.

Your annotations say to me that you have a general idea of what you want to accomplish, but you dont' really need to worry about that at this point, just focus on Development, King Safety, and recognizing opponents threats.  You will start to play much better after you improve in those three areas.

You question black's decision to trade queens on his 8th move.  The merit to this move is that it follows the principle of trading down when up in material.

What do you mean? Alternate moves? Well I'm not exactly an opening expert but I think he's right, e4 allows him to easily challenge your centre and give you problems developing (or in this game win a pawn). 6. Be3 may be better, but eventually you may end up with an isolated pawn.

10. Nc5 is an obvious mistake. Bc2 or Ng3 (gaining a tempo on the bishop) are better, not sure on the best move though. At move 11 you still have  a chance to save the knight by retreating.

Instead of 12. g4 I might play Bb3 taking up a great diagonal and getting the bishop off the back rank with the aim of connecting the rooks.

13. I'm not sure what you mean 'for further rook invasion at b -d7'.

14. You're losing the pawn if you don't defend it. Either capture the knight with the bishop or play h3. Be3 not only hangs the pawn but also weakens your pawn structure further. Just as importantly, you're behind a piece, so you should avoid roughly equal trades where the piece advantage has more of an effect.

Move 17 loses instantly but there's not much you can do, he holds the only open file, you can't really challenge it as he will be more than happy to trade and you don't have any counterplay. The game is over.

I agree with jwhite. You seem to very focused on the strategic aspects, to the dentriment of tactics. While you are blundering pieces strategy is not as important.

So I checked the book openings and 2. Nc3 is called the veresov attack.  It's playable but I still don't like it.  The 3. e4 move is not in the game explorer and I'm sure it's because of the reasons that I gave in my previous post.

If 2...d6 instead of f6 then it's French after 3.e4.

http://www.chess.com/echess/game.html?id=55236498