That's a relief. When you write a game with a somewhat different concept, you're never sure whether players will get it or not. I have fixed the needles bug and the sound on/off issue and am doing a number of other changes based on the feedback I received from you and Adventuron. Thank you both! It's getting late here, so I probably won't get it finished and tested tonight, but certainly tomorrow night.
Unfortunately, I had no choice with the abrupt ending, as it's part of the rules. As soon as you drop the last treasure, the game ends. No further actions or puzzles are allowed. I hope the end-game message made sense, though. (A little bit of a twist!)