Honestly that's not what I expected to hear about the story. If it wasn't a focus why did you include so many unnecessary details? I assumed that was a relic of stripping down the story so details that used to be relevant aren't anymore, that you had become invested in the world and that's why you were hesitant to cut details. As is I have absolutely no idea how you ended with this story. If you didn't care too much about the story, it would be better to keep it to a bare minimum, if anything at all. Honestly you could have replaced the story screen with a tutorial screen and significantly improved the opening experience.
The comment about the art hurting my eyes was somewhat of a throwaway comment, but it's not a useless piece of criticism. What kind of art hurts people's eyes? Either intrusive over-the-top colors or high amounts of contrast where it doesn't belong. Well, your colors aren't over the top, if anything they're mostly gray and brown, so what does that say? The message is that the style is too noisy, it has too much contrast all over the screen in places it doesn't need to be.
Again, assuming you weren't using the tools available was kind of the generous interpretation. If you were using the tools available to you I have no idea how you were spending your time since it clearly wasn't on the story, the art, the sound, the gameplay, or the programming. I'd like to tell you what I think you should have done differently, but that doesn't work when I have no idea what you did. Maybe this was a casual project done in a few hours, but as a 48 hour project done by 2 people? I don't know how old you are or how much experience you have, but I made a 2D platformer from scratch in java in about that much time just after my freshman year of college, it was garbage, but the vast majority of the time was spent getting basic physics and collisions working, and most of the rest of the time was getting stuff to draw correctly.
I'm trying to be polite but that's very difficult here. This game is the worst one I've seen out of any of the gmtk submissions I played, aside from a few that were just completely nonfunctional. You ended up with a game that would be forgettable if it came out in 2008 as a flash game, working with tools that are so far beyond what anyone had back then. I know a lot of times these comment sections get filled up with hollow praise, and who knows maybe that's good for motivation, but honestly I think you could do much better. I mean, the "health as mana" thing isn't a bad idea, it's just not remotely original. Maybe it would have been more creative if you could use it a different way, how about "health is tied to screen position"? Every step you take rightward you need to offset with additional health potions. How about instead of "spells cost health" you had several bars, a health bar a magic bar an energy bar, and if any of them ran out you'd die, so it became more of a game about juggling multiple bars.
I apologize if my criticisms aren't constructive, but honestly I think they are. I tried to pair every criticism I gave with a suggestion on what could have been done differently. Now, maybe that suggestion is garbage, I don't know, and you can disagree with my assessment, but I am truly trying to help. Normally I would try and include as much as possible that I thought you did right, but honestly I can't think of anything that I could say. I know that sounds cruel but I can't think of any other way to say it. I saw another comment say this game was very "ambitious", but I don't even think is accurate considering it's really just trying to be a side-scrolling platformer. All I saw in the comments before I posted was unhelpful faint nonspecific praise, so while I apologize for being harsh, I think it's necessary. I may have done poorly though, since it seems like you've gotten fixated on a few specific criticisms that were worded particularly harshly and didn't see the suggestions that were meant to be more important.
The story was ripped from one of our DnD campaigns, which is why there's so much detail despite it not being a priority. If your problem with the art is that it's too noisy, then the nice, polite, and constructive way to say that is to say it's too noisy. We are not game devs by trade, so our workflow perhaps isn't as streamlined as it should be. Plus we got a late start do to work and personal factors (we didn't actually start on the game until about mid-day on Saturday). I'm done replying here. I'm well aware the game isn't "good", and I plan to make improvements (including to the main mechanic, which yes I agree wasn't done that well).