He exposed his king and got punished
Edit: I know nothing about grob but i still won
5 c4 is wrong: he had to play 5 e4
I am playing Grob for a few years and I can say that both of you played badly the opening stage. Firstable, white shouldn't play c4 and d4. As white I always go for setup: Nc3, d3, e4, f4 and I am demolishing black players on the kingside.
I think the most annoying system against Grob players is 1. g4 e5 2. Bg2 h5!
TBH Grob is a shitty opening if your opponent plays 1... e5, but it can work very effectively against guys who go with 1. d5 2. e5. I had like hundreds of fast and effective wins with white pieces when black goes with this.
So it's OK opening for lower rated players.
