Super fun mechanics and great style. Perfect fit for the theme too. There are some minor things I would change like making the upwards tether pull a little faster (more fun that way), and making the tether break if you shoot it through a wall. The length of the game seems to outlive the environment and enemies though which get a bit repetitive after the first level and then it just ends up with you getting swarmed by them over and over towards the end. Understandable for a game jam, just my nitpick for improvement. Also the throwing enemies often toss a rock before they're even on screen which can be annoying and the charging enemies can charge immediately after getting hurt which is also a bit frustrating. I got that camera crash bug at the boss like other people got in the comments as well so I can't comment much on the boss battle.
All in all a really really good game and I would love to see this expanded on :)