The act of throwing the iems around is weirdly satisfying, I think it was a realy good call to give them all the super exaggerated physics. I also thought the puzzle was pretty spot on, although I would have liked more places where I had to decide which item to bring (maybe some kind of gate that only one item can go through, idk).
I think my biggest issue was getting stuck and having to restart. It was not obvious to me that R was restart, and so I wasted quite a few runs getting deep and then softlocking myself. This was especially bad since there were a few really tricky maneuvering bits that were just about satisfying the first time but really killed pacing the second time. I realize this would be a bit harder to program, but I would really recommend flashing a "Press R to Restart" prompt if the player gets stuck. If detecting if the player get stuck is too hard, one solution would be to have a quit button on the screen, and bring the prompt up when the player goes to quit the first time.
Apart from that my only gripe was that throwing 4 different items up the same hill got tedious after a while. I wanna stress, despite my irritation it was an enjoyable and fun experience.