Needs severe work
I was a little distracted by the presence of sprite characters in a more detailed environment. I also hope that a red Link is just the stand-in for an original graphic.
The jumps were hard and a little bizarre. I noticed a kind of 'ledge grab' glitch where the character doesn't need to jump all the way up onto a platform to walk across it. I'm no programmer, but fixing that would improve the experience.
I found no reason to kill the enemies because it drained my magic and I found no way to restore it. The one knight you jump to in order to be healed was really difficult, beyond the scope of the combat with the spiders, so that encourages the player to be a little cowardly and avoid combat until they can be sure they will be healed. I also couldn't figure out a way to hurt the boss.
Don't take this as me talking down to you! If you do what I suggest, along with some graphic polishing, you might have a fun game on your hands!