RAYCAST YOUR HOOKSHOT! Trying to aim were the crosshair is going to be when the hook hits, while falling, moving sideways, and the mouse look is slow, is just to much. This is coming from someone who built a first person hookshot game (not for the jam) were you have to launch yourself, switch to a gun, shoot the enemies pursuing you, switch back to the hookshot, and anchor to something before you hit the ground.

I would also suggest mapping hookshot launch and release to separate buttons. (Ctrl release left, Spacebar release right, alt is jump because no one jumps when they could be swinging like Spiderman.) When I'm in free fall and launching both hooks madly at anything near me, I don't want to click one too many times and release just as I was about to save myself. This scenario never actually happened due to the very fast gravity which caused a single missed hook to always lead to a fall to my implied death. 

Also, an indicator of what is within range and can be grappled vs too far away and laughing at you as you fall would be nice. My slapdash but quick solution was to place a semitransparent sphere around the player and scale it to match the hookshot's limits. This makes it so everything outside the limit has a tint to it. Some post-processing effect would look better but take far to long to implement.

More air control and moving the kill box below the level a little lower would also help.

I do like the idea of having 2 hookshots and the levels look nice. The slow time mechanic with the changeable platforms is interesting and used well in the levels. I do like hookshot games (that's why I made one,) but I just don't feel like I really have control of my player when I am playing yours.