This is a game I played about a month ago, on the last (6th) round of a local 61 0 B group tournament. I had 4 points out of 5 and it was the 3rd game of a very tiring matchday.

I was playing white and went off to a horrible start, but my opponent let a winning position go with a couple unnecessary sacrifices. The first sac was perhaps ok, but the second one was just a no-no. Enjoy and leave comments!

Some stupid moves by black.  Personally, I think it was a tough game to follow.  Good job in keeping him pressured, though phmilet.

This game can probably be better understood by 1800+ players (in chess.com rating), but if you have any doubts on the reason behind some of the moves i can try to explain it to you.

Those sacrifices did seem a bit risky. And they were.

I have a similar game going on at the moment- my opponent has lost a bishop and a knight and failed to mate me, although they havent given up yet! If you want, when the game is complete I will stick it here as a further example of unsound sacrifices?

But anyway, to your game. You point out all your mistakes, so there isnt a lot to comment on. This game is a lesson for sacrifices though. And here it is, bold for emphasis:

Don't sacrifice pieces until you have found a combination that gives you the edge.

Basically, don't sacrifice your knight just because their king is in a weak position. If they can escape without losses, then the chances are you may have just blundered the game away. And most importantly, just because you've seen a Master sacrifice his bishop in a position that looks similar to yours, doesnt mean its a good idea in your game!

uhurm

don't go to war lack of armor you lose the war

Nytik, you put it perfectly!

My opponent looked at it and it seemed winning, but he saw nothing concrete! You might make a perfect positional or tactical sacrifice, but you gotta see something concrete!

And please do post your game here. May be quite enlightening.

I disagree with the above beliefs that sacrifices need concrete gains.  Maybe it's the chess romantic in me, but I believe the best reason to sacrifice a pawn, piece, whatever the case may be, is to make the game more interesting and, ideally, win.

Interestingly enough, you are pretty much toast even with great play after his knight sacrifice.

19. ... Nc4 20. Qc1 exd3! 21. cxd3 Rxd3

At worst, he equalizes after 22. Bc2 Bxe2 23. Bxd3 Bxd3 =/+, and White is really far behind in development and needs active play to hold his position together at all.  24. Rd8 is probably the best reply but I'm not sure if White can get better than a draw now.

Actually, a sacrifice that leads to a concrete, palpable "gain" is not a sacrifice at all. It's a combination.

Black sacrifices a pawn in this opening (which by the way is theory all the way to move 9, and then still develops in the normal manner for the Two Knights Defense. Then Black gets a huge lead in development. In this case, black opted for a risky continuation, you kept your wits, collected the material offered and beat back the attack. But for a long time the game was in the balance.

I guess it's easy to criticize your opponent after winning a game, but I don't think there was anything too unusual here given the level of the players (similar to my own, though I don't really play on chess.com but on Facebook).

Remember, we're discussing a tournament game here. He could possibly have won with great play after the sacrifice, but was it at all necessary? Tournaments involve some deal of nervousness and tiresomeness, so you might wanna avoid going into sharp lines when you have a simple win.

Besides, I am not criticizing my opponents moves more than I am criticizing my own moves, that put me in this horrible position.

Last, these are not chess.com ratings, those are Rio de Janeiro Chess Federation ratings, and they're a month old. chess.com ratings are somewhat inflated .

Maybe they were blunders OR mistakes rather than sacrifices.

ADK

blunders or your opponent might be sleepy that time and couldnt see those things just like ehat i do when im tired :)

anyways thats natural nobody is perfect....

best wishes