That's what I did, and it wasn't working. I made absolutely sure I was using the fury punch.
I had an excellent time with the rest of the demo, I hope you make more!
I really enjoyed your game. I loved the story, the art and music. Combat was super fun, I had a really good time punching dudes.
My only negative is that I could not deal damage to the first boss. I think it might be bugged. I understand you have to hit him when his stomach opens up to deal damage. Either that, or I am missing something. I am very stupid, so I may have missed something.