Very fun, loved the game play! There's steep incline in difficulty, but I like a good challenge! The check points and random level-up bonuses were also a really nice touch. They made you feel like your were making progress, even when dying multiple times between areas lol.
The things I felt could use a bit more polish were the controls, and some visibility issues while traveling the map.
For visibility - there are a few places where you can get behind the trees and lose track of where you are, it's very easy to get stuck there while dodging enemies.
And for the controls - I was finding it hard to fire, swap elements, and run at the same time. Making the element swap in particular a little faster/more accurate would go a long way for making the more fast paced sections feel more manageable!
Had a good time playing it overall though! Great job!