I'll be honest, it's not too bad!
But i have a few problems, like how the hitboxes can be a problem, you can just be close, but not touching anything, and get hit.
Also, i feel like there should be more healing items other then the pear, because the box attacks do about 5 damage, and the fire do around... 10 to idek, and the pear only heals 10 hp, and the game over music is loud and kind of annoying, but it does have it's pros!
Such as, the sprites and pixels aren't blurry like some other undertale fan-games and such.
And, i like the Jaiden sprite, and the purple background fits, as Jaiden wears a purple shirt in her videos.
And, i think you should make it so it's enter AND the Z key, because in undertale, you can use both, and i prefer to use the Z key.
Overall, i'd rate it a 3.5 out of 5.