To finish the title:
Your opponent only blundered if you punished him for it.
If that isn't already a quote from some historic master, I'm claiming it.
This game is from a Round Robin at Castle Chess in Minneapolis. Time control is 30|5, the fastest USCF regular time control. My opponent, D.P., often plays the French Defense, so I reviewed some games in the Tarrasch Variation this week. I didn't expect 4... c4 (there are only 10 games in chess.com's database), and I did not respond well. Nevertheless, a quick Houdini analysis suggests that I was never more than a "pawn" behind positionally and that the position was often nearly equal until my opponent's first blunder. I seized the opportunity to attack his position, but did not manage to see his second blunder that should have won me the game. Alas, 30|5 is too fast for this poor patzer.
Why didn't I see the win? I was just too focused on his king and trying to figure out how to checkmate him. I assumed that I had enough pieces pointed the right way. Instead of trying to find a brilliant (and nonexistent) sacrifice, I should have looked at the new possible capture and calculated the line. It's clearly winning material at the least.
I hope you enjoy the game.
A complete side note, I look forward to playing in the Sophomore (U1400) section of the MN Open in two weekends. My first "real" tournament, I am overjoyed I will have two hours to make my moves. With a February suppliment of 1000 even, I hope to have a shot at the U1100 prize.