The Borg against d4? Until recently, I played the London System, which served be well and was very solid, but every game I played was very similar and dull.

However, I have now started playing "Grob's Attack" as white, which is 1. g4 as well as "The Borg" as black which goes 1. e4 g5. I have found that these openings are a lot more interesting and my chess games are more fun.

However, now I do not have a response against 1. d4. My question is, if 1. ... g5 is a valid response after 2. bxg5. Keeping in mind I play chess for fun at about the 1500 level, does this line hold any possibilities for black? And if not, do you have any recommendations for an unorthodox aggressive opening against d4?
The position after 1. d4 g5 is close to the worst Black can possibly have after the first move. If you really want to give up a pawn on the first move, the Englund Gambit (1. d4 e5) is better, relatively, without being popular.