Nice work Shibey. Solid worldbuilding/narrative stuff as usual. I liked how you were going for a bit of momentum based platforming with the slide move. Nice run cycle as well.
I think the platforming felt a little rough. You could have a slight period after the player walks off a platform where they can still jump (And not do the double jump). I think the spike hitboxes could also stand to be slightly smaller, or the player hitbox slightly smaller to leave a bit more room for error.
I feel like the ziplines should conserve your momentum, at the moment they just cause you to slow down.
I think in a momentum based platformer it might be better to have the player's attack hitbox be a circle around the player rather than in front.
You could consider having a slight invulnerability after respawning -- in the boss fights I found myself getting killed and then immediately getting killed again.
I felt like the wind was a bit too strong, running against it made you a bit too slow.