Really fun game! The art and sound was great, and the post processing made it feel like I was playing on my old CRT. The character movement was awesome and I was surprised how much you were able to make in the short time of a week with all the different enemies and boss battles.
A couple suggestions, I think the boss battles would benefit if the boss projected was his next attack was going to be. For example, on the fire attacks have a little sprite shoot out in the direction he will attack that doesn't do damage. This gives the player the opportunity to react and they should always feel in control. There were also times where I was taking damage during boss battles and didn't know where it was coming from, again this may just be a visibility thing for the player.
Overall awesome game, great job!