Hi, I would like to know if the Blackmar-Diemer gambit is a good opening choice. Today I played a nice 5 minute attacking game at chess.com. The game is below. What do you think about the opening and its potential?

Ive had real trouble with that opening against master Ive played in my local chess club. They have told me it is unsound.

i've always liked this gambit myself, but i can see how people would say it's unsound.  At the end of the day, i would look at one factor: if you understand the gambit and how to attack with, play it.

The blackmar diemer is "unsound" (you have to be careful with this term since it seems to have different definitions depending on who you ask however in general a gambit from white's perspective is unsound if black can get some kind of advantage it (not necessarily a winning one)).

This means if your opponent ever books up on your opening you will very likely get a bad position, often these gambits can be very effective surprise weapons and might work very well in internet blitz but if your playing seriously in tournaments the rumors will spread fairly fast that you are playing an unsound gambit and your opponents will therefore book up against you.

This is the basic reason why I don't recommend using unsound gambits as a basis for ones repertoire however like I said they can often be good as surprise weapons however there are certain requirements for it to be a good surprise weapon as well which the blackmar doesn't quite live up to in my opinion.

The problem is that it's quite "difficult" for black to go wrong against the blackmar and it's lacking some real sting. Usually what happens is that both sides just develops and we reach a very standard looking middle game where white has a slight initiative for the cost of a pawn (there's very few immediate dangers compared to other unsound gambits like the king's gambit and the danish gambit). And the main problem is just that the position is quite "standard" and therefore most decent players has a fair idea on how they should go about defending the position against white's coming attack and after whites initiative fades away black will just be up a pawn.

The best I could say about the blackmar is that it's quite effective in bullet when your just throwing moves around having quite easy development and a slight initiative helps a lot.

A good surprise weapon should in my opinion have a lot of pitfalls and really put the pressure on your opponent to play the most accurate moves which the blackmar doesn't quite live up to.

I've played a few BDG blitz games online and won quickly, but it probably isn't sound in OTB play. Maybe against a much weaker player...but not as your main opening.

Good game, especially Nxf7

I used to play the Blackmar-Diemer from time as time, as a surprise transposition out of the Scandinavian defense (1.e4 d5 2.d4?!).  I would have thought people playing the Scandinavian in a tournament would have a response prepared for the BDG, but you should've seen some of their faces.

I'd agree with most everything the previous posters have said.  No, it's not really sound; probably even less so than other borderline gambits (Morra Gambit, Latvian Gambit, etc.).  Yes, you might catch some people unaware OTB or in blitz because it's an unconventional opening.  Yes, it's useful to play gambits from time to time to be forced into a mode where you have to make the most of every tempo.  No, I wouldn't suggest using it as the basis of your "serious" repertoire.