I'm not the best player out there but will provide some basic advice.
Also what were the time controls? Was it blitz or turn based?
1. Yes 6.Nxd4 does waste a tempo and exd4 is stronger
2. 10.Bd3 violates the opening principle of never moving the same piece twice. You have already moved your Nf3 3 times in the game and now this bishop twice. Your DSB didn't get a start until after move 20!
3. I wouldn't worry much about 11.h3. Yes it probably wasn't the best move, but it isn't terrible either. Especially in a blitz game, don't regret this and take upon a negative mind set. In this case an open king isn't much of a problem because the queens are off and his pieces are nowhere near you.
4. 14.Nd5 is a bad move. You are trading off a relatively good knight for a sucky one. Their Nf6 has no good squares to go so you should try to keep it bad. Instead develop the DSB
5. 16.Bc2 loses a pawn to Nxf3 so you were correct in playing Be2.
6. Not sure what the point of moves 18 and 19 were. Not necessarily bad, just they don't seem to get you anywhere (except allowing DSB development, but that didn't require a4). I would have gone with Bd2 to get the last piece in play.
7. 26. Rb1 loses are pawn but I'm sure you know this. Rad1 or Bf3 to defend the pawn. Or even Be2! where if your opponent goes Nxd5?, 27.Bc4! wins the knight.
8. 31.b4 was risky. It this is a blitz game then a lower rated opponent is likely to not see 32.a5!. However if they did then your is a lot of trouble
9. 37.fxe5? , 39.Bxg2? 40.Kxg3? Your opponent is blundering pieces. Take them.
10. Your endgame play was far from perfect. Many opportunities to take pieces that you missed completely. Also 43.Ra7 would have been more useful then e4. Also you kept moving your king to where the knight could check you, move your king to a square such that it will take 3 knight moves before they can deliver another check.
Conclusions: I think you played the game rather well. A couple of obvious blunders, but thats to be expected if this game was blitz. Also the endgame took about 10-15 moves longer then it should have if you had taken his pieces. These are just some of my thoughts. There are stronger players who will be able to provide better/ alternative lines to your blunders.
Hey Chess.com! I recently played a very interesting game [or so I believe] against a man named Boris. You can see it below. However, before checking the game out, would it be all right if you kept these questions in mind? • 1. What could I have done better? • 2. Is my opening rusty? • 3. How would one win efficiently with a Queen and Rook vs. Knight and Pawns? [You may find the full questions at the end of the game!]
Thanks for reading! I might post some more games in the future, but this is what I've got for now. Feel free to analyze in the comments... I could use the tips and would be happy to participate in discussion!
Yours Truly,
~ CalbaMan