Not bad! I like the animation of the player.
I think a lot of polish could be helpful. Maybe some control over the attacking, and less of a chance to get injured from a pixel of contact. I also think one big thing would be the visuals, being the consistency of the pixel sizing.
I also wanted to add that it's highly unlikely that a player will last 5 minutes of your game, as attention span is very short.
Other than that, the music is nice, and this game certainly has potential!