The art in your cover is really charming. I was hoping the game would be more like that.
Not sure which art is yours and which came from asset packs or ripped spritesheets.
The main character could use a jumping noise and a walking animation that looks more like walking and less like fighting. I get that he was a boxer in his life, but surely he didn't always walk like that?
Since it's a platformer, one or two more levels would go a long way.