Nice graphics! I included it in my Game Maker Toolkit’s Game Jam compilation video series, if you’d like to take a look. :)

Clever design with the mechanic. I found out how to stun the enemies (dual purpose design, woo!) and make it a bit further than my first playthrough. Can get a bit annoying when you land at a spot that is technically a dead end for progressing further with the grappling hook, making me grapple to a previous spot to progress further. 
Really nice ambiance, visually and audibly!

This is extremely well made and looks pretty cool with the whole lined screen aesthetic, and there's a surprising amount of content for a 48 hour game. Kinda reminds me of The Swapper which is a super underrated puzzle platformer. I would love to see other ways the hook would be used if you developed more content. Maybe some more stationary interactable elements like door triggers or avoiding projectiles etc.