After playing the game i have a few suggestions:
1. While you present the controls, the game already started. You can see the timer going at the top, so you can come back and die even before pressing K to accept.
2. Usually in games with this kind of bar selection for items scrolling down on the mouse wheel makes it go to the next item, not the previous one (it is inverted from the standard).
3. A minimap could help collecting the xp that you may have left over at the ground, and if not, for it to get towards you faster/from a bigger range (maybe this last part as a upgrade?)
4. The boss I've found it and fought it, but all of a sudden started to spam wide area attacks (it changed the attack it was doing to a wider one with a lot more projectiles), and to say that you have to thread the needle there is quite the understatement, as sometimes i wasn't hit (didn't look like it at least) but still received damage. Maybe a text ingame that tells players to go find the boss when no enemies are left could help as well.
5. The fire rod has a small issue, if you equip it and go to the top wall of the map until colliding with it and you try to shoot the fire, it will disappear as soon as you shot it because it collides on spawn with the wall.
6. Lack of sound effects, this could have a huge impact on how the game feels and plays out, please consider adding some if you intend to update/continue the game, unless it was a design choice.
All of those are minor things that all they would need is some adjusting, and this doesn't mean in any way that the game is bad, I hope this helps ;)
Cool game and design, fun to play! Cheers :D