The pixel art is fantastic, the whole game is very visually appealing. The music fits well and the sound effects are a nice touch. Movement feels responsive and the swinging mechanic works well. I do think some kind of visual feedback is needed for the players E attack although from your comment it sounds like this was planned.
My only critique would be that the world feels a little bit sparse, the characters/objects are quite small on the screen - bullets in particular feel tiny and hard to dodge because of it. However saying this the miscellaneous details like barrels, cacti and rocks really help to make the level feel less monotonous.
Overall an excellent submission, really well done!