Blunder or Not?

Basically I did a Knight sacrifice and apparently it's a blunder despite it being a checkmate in the next 2 moves

I was supposed to send a pic here

White blundered into checkmate by playing 13. Ke1? ... Avoiding checkmate with13. Kc2 ... instead is completely winning for White, so giving away Black's knight was a blunder.

Fair point

In all fairness, I think it has a lot to do with experience/expectations. You two are around 200 ELO. I thought it was a clever move for a game at that range. So good job on the win!

Of course, technically it was a blunder because you gave up material and the mate could have been avoided, as was pointed out. But I think it is great that you found the plan and executed it. As you move up in experience and ratings, your opponents will become more observant and calculating and so you will need to make more clever plans that aren't so easily avoided (at least if you are giving up a piece to try it). But that is the future. For now, enjoy the win!

Keep playing like this, and you'll be 800

If the guy keeps throwing away pieces, the rating will go down, not up.

This game is a good example why low rated players are advised to not sacrifice anything.

Yes, because it is not a check mate. White does not have to go to e1 as he can just go to c2 and the game continues.